Remove circular dependency between ComponentManager and Component.
Remove circular dependency of Component from Animation class.
Fix comments in ComponentManagerSpec.js
Remove circular dependency in Layout and Container classes by introducing LayoutManager and the Layout.isGuiLayout property.

The property is so the Layout class does not need to be require()'d in a module just to run an instanceof check.
Latest build files for 0.8.6, which remove the circular dependencies from the library.