GUI Wrapper

Based on android model of a touch listener.
-GUIManager, the main class which keeps track of each GUI element and
renders them via RenderGUIObjects. Requires instance of this class to
check for null.
-Added EventHandler to GUIManager to pass which button label has been
pressed.
-Supported GUI Objects: Button and Label.

Note: GUIProperties and ButtonName are used in conjunction with
GUIManager.

Other changes:
-Converted texttoggles into an array for terrains in LevelEditorUI