Qualify all item slugs to the mod which adds them #53

* Change default item URL to fall under /mod/<mod slug>/<item slug>
  but kept the old URL pattern around with the old behavior (i.e.,
  find the first item with that slug)
* Update Item to have a `qualifiedSlug` property which combines the
  item's own slug with its Mod's slug.  Updated a lot of code all
  over to use this in preference to the plain slug.
* Add a `localizeTo` method to Inventory to allow non-qualified slugs
  to be converted into qualified slugs within the inventory's stacks
* Update ModPack to work with either qualified or unqualified slugs
  for relevant methods
* Fix model state changes to happen before related events are
  triggered
* Add a debounce to the CraftingPlan object when triggering a recraft
  due to changes in related objects (esp. its inventories)
* Update the Inventory's sort to keep items sorted by mod before name
  with the Minecraft items sorted to the top
* Fix `ModPack.findItemByName` to actually recursively use the Mod's
  method instead of slugifying the given name and looking for the
  slug (since this won't necessarily work anymore).
* Ensure each Mod is assigned a reference to its containing ModPack
* Fix NameFinder to only consider an item non-gatherable if it is
  also craftable
* Update ModVersionParserV1 to assign qualified slugs to recipes
  for any items which are in the same mod (leaving any other slugs
  unqualified)
* Add Underscore mixins for composing and decomposing slugs
* Update old tests for the use of qualified slugs, and some new tests
  for the new methods added

src/scripts/controllers/item_page_controller.coffee

@@ -57,7 +57,7 @@ module.exports = class ItemPageController extends BaseController
         $('title').html if @model.item? then "#{@model.item.name} | #{Text.title}" else Text.title
         @_resolveItemSlug()
 
-        display = @_modPack.findItemDisplay @model.item?.slug
+        display = @_modPack.findItemDisplay @model.item?.qualifiedSlug
         if display?
             @$craftingPlanLink.attr href:display.craftingUrl
             @$craftingPlanLink.fadeIn duration:Duration.normal
@@ -143,6 +143,4 @@ module.exports = class ItemPageController extends BaseController
             @$similarContainer.fadeOut duration:Duration.normal
 
     _resolveItemSlug: ->
-        oldItem = @model.item
         @model.item = @_modPack.findItem @_itemSlug, includeDisabled:true
-        newItem = @model.item