Add Document#slug

lib/jekyll/document.rb

@@ -45,6 +45,15 @@ module Jekyll
       File.basename(path, suffix)
     end
 
+    # The sluggified base filename of the document.
+    #
+    # Returns the base filename of the document in lowercase, with every
+    # sequence of spaces and non-alphanumeric characters replaced with a
+    # hyphen.
+    def slug
+      File.basename(path, ".*").downcase.gsub(/[\W\s]+/, '-')
+    end
+
     # The extension name of the document.
     #
     # Returns the extension name of the document.
@@ -129,7 +138,7 @@ module Jekyll
         collection: collection.label,
         path:       cleaned_relative_path,
         output_ext: Jekyll::Renderer.new(site, self).output_ext,
-        name:       basename(".*")
+        name:       slug
       }
     end