1. Moved _plugins into themes/classic/_plugins

I think it's probably better to ship plugins with themes to make it
easier to update them.
2. Improved 'install' rake task and made nicer output

Rakefile

@@ -25,9 +25,13 @@ task :install, :theme do |t, args|
   # copy theme into working Jekyll directories
   theme = args.theme || 'classic'
   puts "## Copying "+theme+" theme to Jekyll paths"
-  system "cp -R themes/"+theme+"/source source"
+  system "mkdir -p #{source}; cp -R themes/"+theme+"/source/ #{source}/"
-  system "cp -R themes/"+theme+"/sass sass"
+  system "mkdir -p sass; cp -R themes/"+theme+"/sass/ sass/"
-  # system "cp -R themes/"+theme+"/_plugins/ _plugins/"
+  system "mkdir -p _plugins; cp -R themes/"+theme+"/_plugins/ _plugins/"
+  system "mkdir -p #{source}/_posts";
+  puts "## Layouts, images, and javascritps from the #{theme} theme have been installed into ./#{source}"
+  puts "## Sass stylesheet sources from the #{theme} theme have been installed into ./sass"
+  puts "## Plugins from the #{theme} theme have been installed into ./_plugins"
 end
 
 #######################

themes/classic/_plugins/sitemap_generator.rb

@@ -0,0 +1,309 @@
+# Sitemap.xml Generator is a Jekyll plugin that generates a sitemap.xml file by
+# traversing all of the available posts and pages.
+#
+# How To Use:
+#   1.) Copy source file into your _plugins folder within your Jekyll project.
+#   2.) Change MY_URL to reflect your domain name.
+#   3.) Change SITEMAP_FILE_NAME if you want your sitemap to be called something
+#       other than sitemap.xml.
+#   4.) Change the PAGES_INCLUDE_POSTS list to include any pages that are looping
+#       through your posts (e.g. "index.html", "archive.html", etc.). This will
+#       ensure that right after you make a new post, the last modified date will
+#       be updated to reflect the new post.
+#   5.) Run Jekyll: jekyll --server to re-generate your site.
+#   6.) A sitemap.xml should be included in your _site folder.
+#
+# Customizations:
+#   1.) If there are any files you don't want included in the sitemap, add them
+#       to the EXCLUDED_FILES list. The name should match the name of the source
+#       file.
+#   2.) If you want to include the optional changefreq and priority attributes,
+#       simply include custom variables in the YAML Front Matter of that file.
+#       The names of these custom variables are defined below in the
+#       CHANGE_FREQUENCY_CUSTOM_VARIABLE_NAME and PRIORITY_CUSTOM_VARIABLE_NAME
+#       constants.
+#
+# Notes:
+#   1.) The last modified date is determined by the latest from the following:
+#       system modified date of the page or post, system modified date of
+#       included layout, system modified date of included layout within that
+#       layout, ...
+#
+# Author: Michael Levin
+# Site: http://www.kinnetica.com
+# Distributed Under A Creative Commons License
+#   - http://creativecommons.org/licenses/by/3.0/
+
+require 'rexml/document'
+
+module Jekyll
+
+  # Change MY_URL to reflect the site you are using
+  MY_URL = "http://www.mysite.com"
+
+  # Change SITEMAP_FILE_NAME if you would like your sitemap file
+  # to be called something else
+  SITEMAP_FILE_NAME = "sitemap.xml"
+
+  # Any files to exclude from being included in the sitemap.xml
+  EXCLUDED_FILES = ["atom.xml"]
+
+  # Any files that include posts, so that when a new post is added, the last
+  # modified date of these pages should take that into account
+  PAGES_INCLUDE_POSTS = ["index.html"]
+
+  # Custom variable names for changefreq and priority elements
+  # These names are used within the YAML Front Matter of pages or posts
+  # for which you want to include these properties
+  CHANGE_FREQUENCY_CUSTOM_VARIABLE_NAME = "change_frequency"
+  PRIORITY_CUSTOM_VARIABLE_NAME = "priority"
+
+  class Post
+    attr_accessor :name
+
+    def full_path_to_source
+      File.join(@base, @name)
+    end
+
+    def location_on_server
+      "#{MY_URL}#{url}"
+    end
+  end
+
+  class Page
+    attr_accessor :name
+
+    def full_path_to_source
+      File.join(@base, @dir, @name)
+    end
+
+    def location_on_server
+      location = "#{MY_URL}#{@dir}#{url}"
+      location.gsub(/index.html$/, "")
+    end
+  end
+
+  class Layout
+    def full_path_to_source
+      File.join(@base, @name)
+    end
+  end
+
+  # Recover from strange exception when starting server without --auto
+  class SitemapFile < StaticFile
+    def write(dest)
+      begin
+        super(dest)
+      rescue
+      end
+
+      true
+    end
+  end
+
+  class SitemapGenerator < Generator
+
+    # Valid values allowed by sitemap.xml spec for change frequencies
+    VALID_CHANGE_FREQUENCY_VALUES = ["always", "hourly", "daily", "weekly",
+      "monthly", "yearly", "never"]
+
+    # Goes through pages and posts and generates sitemap.xml file
+    #
+    # Returns nothing
+    def generate(site)
+      sitemap = REXML::Document.new << REXML::XMLDecl.new("1.0", "UTF-8")
+
+      urlset = REXML::Element.new "urlset"
+      urlset.add_attribute("xmlns",
+        "http://www.sitemaps.org/schemas/sitemap/0.9")
+
+      @last_modified_post_date = fill_posts(site, urlset)
+      fill_pages(site, urlset)
+
+      sitemap.add_element(urlset)
+
+      # File I/O: create sitemap.xml file and write out pretty-printed XML
+      file = File.new(File.join(site.dest, SITEMAP_FILE_NAME), "w")
+      formatter = REXML::Formatters::Pretty.new(4)
+      formatter.compact = true
+      formatter.write(sitemap, file)
+      file.close
+
+      # Keep the sitemap.xml file from being cleaned by Jekyll
+      site.static_files << Jekyll::SitemapFile.new(site, site.dest, "/", SITEMAP_FILE_NAME)
+    end
+
+    # Create url elements for all the posts and find the date of the latest one
+    #
+    # Returns last_modified_date of latest post
+    def fill_posts(site, urlset)
+      last_modified_date = nil
+      site.posts.each do |post|
+        if !excluded?(post.name)
+          url = fill_url(site, post)
+          urlset.add_element(url)
+        end
+
+        path = post.full_path_to_source
+        date = File.mtime(path)
+        last_modified_date = date if last_modified_date == nil or date > last_modified_date
+      end
+
+      last_modified_date
+    end
+
+    # Create url elements for all the normal pages and find the date of the
+    # index to use with the pagination pages
+    #
+    # Returns last_modified_date of index page
+    def fill_pages(site, urlset)
+      site.pages.each do |page|
+        if !excluded?(page.name)
+          path = page.full_path_to_source
+          if File.exists?(path)
+            url = fill_url(site, page)
+            urlset.add_element(url)
+          end
+        end
+      end
+    end
+
+    # Fill data of each URL element: location, last modified,
+    # change frequency (optional), and priority.
+    #
+    # Returns url REXML::Element
+    def fill_url(site, page_or_post)
+      url = REXML::Element.new "url"
+
+      loc = fill_location(page_or_post)
+      url.add_element(loc)
+
+      lastmod = fill_last_modified(site, page_or_post)
+      url.add_element(lastmod) if lastmod
+
+      if (page_or_post.data[CHANGE_FREQUENCY_CUSTOM_VARIABLE_NAME])
+        change_frequency =
+          page_or_post.data[CHANGE_FREQUENCY_CUSTOM_VARIABLE_NAME].downcase
+
+        if (valid_change_frequency?(change_frequency))
+          changefreq = REXML::Element.new "changefreq"
+          changefreq.text = change_frequency
+          url.add_element(changefreq)
+        else
+          puts "ERROR: Invalid Change Frequency In #{page_or_post.name}"
+        end
+      end
+
+      if (page_or_post.data[PRIORITY_CUSTOM_VARIABLE_NAME])
+        priority_value = page_or_post.data[PRIORITY_CUSTOM_VARIABLE_NAME]
+        if valid_priority?(priority_value)
+          priority = REXML::Element.new "priority"
+          priority.text = page_or_post.data[PRIORITY_CUSTOM_VARIABLE_NAME]
+          url.add_element(priority)
+        else
+          puts "ERROR: Invalid Priority In #{page_or_post.name}"
+        end
+      end
+
+      url
+    end
+
+    # Get URL location of page or post
+    #
+    # Returns the location of the page or post
+    def fill_location(page_or_post)
+      loc = REXML::Element.new "loc"
+      loc.text = page_or_post.location_on_server
+
+      loc
+    end
+
+    # Fill lastmod XML element with the last modified date for the page or post.
+    #
+    # Returns lastmod REXML::Element or nil
+    def fill_last_modified(site, page_or_post)
+      path = page_or_post.full_path_to_source
+
+      lastmod = REXML::Element.new "lastmod"
+      date = File.mtime(path)
+      latest_date = find_latest_date(date, site, page_or_post)
+
+      if @last_modified_post_date == nil
+        # This is a post
+        lastmod.text = latest_date.iso8601
+      else
+        # This is a page
+        if posts_included?(page_or_post.name)
+          # We want to take into account the last post date
+          final_date = greater_date(latest_date, @last_modified_post_date)
+          lastmod.text = final_date.iso8601
+        else
+          lastmod.text = latest_date.iso8601
+        end
+      end
+      lastmod
+    end
+
+    # Go through the page/post and any implemented layouts and get the latest
+    # modified date
+    #
+    # Returns formatted output of latest date of page/post and any used layouts
+    def find_latest_date(latest_date, site, page_or_post)
+      layouts = site.layouts
+      layout = layouts[page_or_post.data["layout"]]
+      while layout
+        path = layout.full_path_to_source
+        date = File.mtime(path)
+
+        latest_date = date if (date > latest_date)
+
+        layout = layouts[layout.data["layout"]]
+      end
+
+      latest_date
+    end
+
+    # Which of the two dates is later
+    #
+    # Returns latest of two dates
+    def greater_date(date1, date2)
+      if (date1 >= date2)
+        date1
+      else
+        date2
+      end
+    end
+
+    # Is the page or post listed as something we want to exclude?
+    #
+    # Returns boolean
+    def excluded?(name)
+      EXCLUDED_FILES.include? name
+    end
+
+    def posts_included?(name)
+      PAGES_INCLUDE_POSTS.include? name
+    end
+
+    # Is the change frequency value provided valid according to the spec
+    #
+    # Returns boolean
+    def valid_change_frequency?(change_frequency)
+      VALID_CHANGE_FREQUENCY_VALUES.include? change_frequency
+    end
+
+    # Is the priority value provided valid according to the spec
+    #
+    # Returns boolean
+    def valid_priority?(priority)
+      begin
+        priority_val = Float(priority)
+        return true if priority_val >= 0.0 and priority_val <= 1.0
+      rescue ArgumentError
+      end
+
+      false
+    end
+  end
+end
+