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/inventory_parser.test.coffee

@@ -24,7 +24,7 @@ describe 'inventory_parser.coffee', ->
         result.toList().should.eql []
 
     it 'can parse a single item without quantity', ->
-        result = parser.parse 'Wool'
+        result = parser.parse 'wool'
         result.toList().should.eql ['wool']
 
     it 'can parse a single item with quantity', ->
@@ -32,11 +32,11 @@ describe 'inventory_parser.coffee', ->
         result.toList().should.eql [[4, 'wool']]
 
     it 'can parse multiple mixed-type items', ->
-        result = parser.parse '4.Wool:10.String:Boat'
+        result = parser.parse '4.wool:10.string:boat'
         result.toList().should.eql ['boat', [10, 'string'], [4, 'wool']]
 
     it 're-uses the given inventory object', ->
         inventory = new Inventory
         inventory.add 'string', 8
-        result = parser.parse '4.Wool', inventory
+        result = parser.parse '4.wool', inventory
         result.toList().should.eql [[8, 'string'], [4, 'wool']]