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

test/recipe.test.coffee

@@ -5,6 +5,7 @@ Copyright (c) 2015 by Redwood Labs
 All rights reserved.
 ###
 
+Item   = require '../src/scripts/models/item'
 Recipe = require '../src/scripts/models/recipe'
 Stack  = require '../src/scripts/models/stack'
 
@@ -32,7 +33,8 @@ describe 'recipe.coffee', ->
             expect(-> new Recipe name:'Gold Gear', input:input).to.throw Error, 'attributes.pattern is required'
 
         it 'allows an item to provide required attributes', ->
-            recipe = new Recipe item:{name:'Gold Gear', slug:'gold_gear'}, input:input, pattern:pattern
+            item = new Item name:'Gold Gear'
+            recipe = new Recipe item:item, input:input, pattern:pattern
             recipe.name.should.equal 'Gold Gear'
             (o.slug for o in recipe.output).should.eql ['gold_gear']