Fix order.
Added new methods to GUI. Changed TimeProvider implementation to use System.nanoTime() instead.
Remove Nifty GUI and demos.
Remove more Nifty gui classes. Add DefaultGuiRenderer.java.
Remove NiftyGuiRenderer.java
Use interface instead of abstract class.
Remove AbstractGuiScreen.java
Remove Nifty assets. Do nothing during update.
Rely on Fw.graphics instead of duplicating switching renderers for the pipeline.