Add code to build crafting trees

src/coffee/models/crafting/item_node.coffee

@@ -0,0 +1,69 @@
+###
+Crafting Guide - item_node.coffee
+
+Copyright (c) 2015 by Redwood Labs
+All rights reserved.
+###
+
+CraftingNode = require './crafting_node'
+RecipeNode   = require './recipe_node'
+
+########################################################################################################################
+
+module.exports = class ItemNode extends CraftingNode
+
+    constructor: (options={})->
+        if not options.item? then throw new Error 'options.item is required'
+        super options
+
+        @item = options.item
+        @_recipes = null
+
+    # Property Methods #############################################################################
+
+    getRecipes: ->
+        if not @_recipes?
+            @_recipes = @modPack.findRecipes @item.slug
+        return @_recipes or []
+
+    isGatherable: ->
+        return true if @item.isGatherable
+        return true unless @getRecipes().length > 0
+        return false
+
+    Object.defineProperties @prototype,
+        gatherable: { get:@prototype.isGatherable }
+        recipes: { get:@prototype.getRecipes }
+
+    # CraftingNode Overrides #######################################################################
+
+    _createChildren: (result=[])->
+        recipes = @getRecipes()
+        return [] unless recipes.length > 0
+
+        for recipe in recipes
+            result.push new RecipeNode modPack:@modPack, recipe:recipe
+
+        return result
+
+    _checkCompleteness: ->
+        return true if @gatherable
+        return false unless @children?
+
+        for child in @children
+            return true if child.isComplete
+        return false
+
+    _checkValidity: ->
+        for child in @children
+            return true if child.isValid
+
+    # Object Overrides #############################################################################
+
+    toString: (indent)->
+        completeText = if @complete then 'complete' else 'incomplete'
+        parts = ["#{indent}#{@completeText} ItemNode for #{@item.name}"]
+        nextIndent = indent + '    '
+        for child in @children
+            parts.push child.toString nextIndent
+        return parts.join '\n'