Show markdown description text on item detail page

* Update build process to *not* copy over prerendered pages during a
  regular build (only during a `dist` build)
* Add dependency on npm "markdown" package and include it in the
  scripts loaded in the default layout
* Update the Item model to be able to load from a *.cg file
* Add an ItemParser to process the `item.cg` file
* Update the general parser to be able to work with HereDoc-style
  text blocks
* Add a markdown-specific stylesheet
* Add a sample of the `item.cg` file format (Advanced Crafting Table)

src/coffee/controllers/item_controller.coffee

@@ -18,8 +18,8 @@ module.exports = class ItemController extends BaseController
         options.templateName = 'item'
         super options
 
-        @_imageLoader = options.imageLoader
-        @_modPack     = options.modPack
+        @imageLoader = options.imageLoader
+        @modPack     = options.modPack
 
     # BaseController Overrides #####################################################################
 
@@ -30,9 +30,9 @@ module.exports = class ItemController extends BaseController
         super
 
     refresh: ->
-        display = @_modPack.findItemDisplay @model.slug
+        display = @modPack.findItemDisplay @model.slug
 
-        @_imageLoader.load display.iconUrl, @$icon
+        @imageLoader.load display.iconUrl, @$icon
         @$name.html display.itemName
         @$nameLink.attr 'href', display.itemUrl