Add local storage for certain UI state

src/scripts/models/mod_pack.coffee

@@ -115,7 +115,11 @@ module.exports = class ModPack extends BaseModel
     loadModVersionData: (data)->
         modVersion = @_parser.parse data
         @modVersions.push modVersion
+        @trigger Event.add, modVersion, this
+
         @modVersions.sort (a, b)-> a.compareTo b
+        @trigger Event.sort, this
+
         modVersion.on Event.change, => @trigger Event.change, this
 
         return modVersion

src/scripts/models/storage.coffee

@@ -0,0 +1,51 @@
+###
+Crafting Guide - storage.coffee
+
+Copyright (c) 2015 by Redwood Labs
+All rights reserved.
+###
+
+########################################################################################################################
+
+module.exports = class Storage
+
+    constructor: (options={})->
+        options.storage ?= window.sessionStorage
+
+        @storage = options.storage
+        @_models = {}
+
+    # Public Methods ###############################################################################
+
+    register: (key, model, properties...)->
+        modelData = @_models[key]
+        if not modelData? then modelData = @_models[key] = model:model, properties:{}
+        makeStoreMethod = (k, m, p)=> return => @_store(k, m, p)
+
+        for property in properties
+            continue if modelData.properties[property]?
+            modelData.properties[property] = property
+
+            @_load key, model, property
+            model.on "change:#{property}", makeStoreMethod(key, model, property)
+
+    unregister: (key, property)->
+        modelData = @_models[key]
+        return unless modelData?
+        delete modelData.properties[key]
+
+    # Private Methods ##############################################################################
+
+    _load: (key, model, property)->
+        value = @storage.getItem "#{key}:#{property}"
+        value = JSON.parse(value) if value?
+
+        logger.verbose "loaded #{value} from #{key}:#{property}"
+        return unless value?
+
+        model[property] = value
+
+    _store: (key, model, property)->
+        value = JSON.stringify model[property]
+        @storage.setItem "#{key}:#{property}", value
+        logger.verbose "stored #{value} into #{key}:#{property}"