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/models/item.coffee

@@ -21,28 +21,33 @@ module.exports = class Item extends BaseModel
 
         attributes.group        ?= Item.Group.Other
         attributes.isGatherable ?= false
+        attributes.modVersion   ?= null
         attributes.slug         ?= _.slugify attributes.name
+
         options.logEvents       ?= false
         super attributes, options
 
         @_recipes = []
+
         Object.defineProperties this,
             isCraftable:   { get:-> @_recipes.length > 0 }
+            qualifiedSlug:      { get:@getQualifiedSlug }
             primaryRecipe: { get:@getPrimaryRecipe }
 
+        @on Event.change + ':modVersion', => @_qualifiedSlug = null
+
     # Public Methods ###############################################################################
 
     addRecipe: (recipe)->
-        if recipe.slug isnt @slug then throw new Error "cannot add a recipe for #{recipe.slug} to #{@slug}"
+        [modSlug, itemSlug] = _.decomposeSlug recipe.slug
+        if itemSlug isnt @slug then throw new Error "cannot add a recipe for #{recipe.slug} to #{@slug}"
+        recipe.item = this
         @_recipes.push recipe
 
     eachRecipe: (callback)->
         for recipe in @_recipes
             callback recipe
 
-    getPrimaryRecipe: ->
-        return @_recipes[0]
-
     compareTo: (that)->
         if this.slug isnt that.slug
             return if this.slug < that.slug then -1 else +1
@@ -50,6 +55,19 @@ module.exports = class Item extends BaseModel
             return if this.name < that.name then -1 else +1
         return 0
 
+    # Property Methods #############################################################################
+
+    getQualifiedSlug: ->
+        return @slug if not @modVersion?
+
+        if not @_qualifiedSlug?
+            @_qualifiedSlug = _.composeSlugs @modVersion.modSlug, @slug
+
+        return @_qualifiedSlug
+
+    getPrimaryRecipe: ->
+        return @_recipes[0]
+
     # Object Overrides #############################################################################
 
     toString: ->