Allow item stacks as input for recipes

* Create the SlotController and refactor it into the various places
  where a crafting grid or crafting output is displayed
* Update the Recipe model to allow each "input" stack to retain the
  count indicated in the data file. This required changing how a few
  other classes interact with it in order for them to get the full
  stack back again for each input (instead of just getting the item
  slug)
* Update the ModVersionParser to allow for full stacks to be given
  as input and refactored common code out for handling input/output/
  tools stacks

src/jade/templates/crafting_grid.jade

@@ -7,14 +7,14 @@
 
 table.view__crafting_grid
     tr
-        td: a: img(src="/images/empty.png")
-        td: a: img(src="/images/empty.png")
-        td: a: img(src="/images/empty.png")
+        td: .view__slot
+        td: .view__slot
+        td: .view__slot
     tr
-        td: a: img(src="/images/empty.png")
-        td: a: img(src="/images/empty.png")
-        td: a: img(src="/images/empty.png")
+        td: .view__slot
+        td: .view__slot
+        td: .view__slot
     tr
-        td: a: img(src="/images/empty.png")
-        td: a: img(src="/images/empty.png")
-        td: a: img(src="/images/empty.png")
+        td: .view__slot
+        td: .view__slot
+        td: .view__slot

src/jade/templates/minimal_recipe.jade

@@ -9,6 +9,4 @@
     .input
         table.view__crafting_grid
         .tool
-    .output
-        a: img
-        p.quantity
+    .output.view__slot

src/jade/templates/slot.jade

@@ -0,0 +1,11 @@
+//-
+//- Crafting Guide - slot.jade
+//-
+//- Copyright (c) 2015 by Redwood Labs
+//- All rights reserved.
+//-
+
+.view__slot
+    a
+        img.hideable.hiding
+        .quantity