Added utility function to create facet classes

 - Similar in utility to the 'createComponentClass' already implemented

lib/milo.js

@@ -65,6 +65,7 @@ _.extend(milo, {
     registry: require('./registry'),
     milo_version: '0.2.6',
     createComponentClass: require('./util/create_component_class'),
+    createFacetClass: require('./util/create_facet_class'),
     destroy: destroy
 });
 

lib/util/create_facet_class.js

@@ -0,0 +1,27 @@
+'use strict';
+
+var miloCore = require('milo-core')
+    , _ = miloCore.proto
+    , check = miloCore.util.check
+    , Match = check.Match
+    , FacetBaseClass = require('../components/c_facet')
+    , facetRegistry = require('../components/c_facets/cf_registry');
+
+module.exports = createFacetClass;
+
+function createFacetClass(config) {
+    check(config, {
+        className: String,
+        superClassName: Match.Optional(String),
+        methods: Match.Optional(Match.ObjectHash(Function))
+    });
+
+    var SuperClass = config.superClassName ? facetRegistry.get(config.superClassName) : FacetBaseClass;
+    var FacetClass = _.createSubclass(SuperClass, config.className);
+
+    if (config.methods) _.extendProto(FacetClass, config.methods);
+
+    FacetClass.super = SuperClass.prototype;
+    facetRegistry.add(FacetClass);
+    return FacetClass;
+}