Complete refactoring to move Recipes into Items

* Changed "version" to "dataVersion" in data format
* Changed the "modName" and "modVersion" fields on the ModVersion
  class to remove the "mod" prefix and changed the data format to
  match
* Change the Stack class to use the itemSlug instead of the item
  itself
* Update the ModVersion and ModPack classes to include methods for
  recording a correspondence between slugs and names. Update code
  which displays items from stacks to use these methods to determine
  display names.
* Add a reference from Recipe back to the item it creates

src/scripts/models/inventory_parser.coffee

@@ -25,6 +25,6 @@ module.exports = class InventoryParser
             quantity = if match? then parseInt(match[1]) else 1
 
             if name.length > 0
-                inventory.add new Item(name:name), quantity
+                inventory.add _.slugify(name), quantity
 
         return inventory