Remove GameBase GL context accessor and make Texture loading require a GL object
Add functionality to 'consume' input
Switch Material to store textures by their integer ID instead of by Texture object
Clean up and rename the Material creation function 'getPixel'
Add computation of solidity maps on sprite load
Add initial UIElement update/draw support:
Remove unnecessary UI code
Add focus data to UIElement
Move all animation code to Animatable
Shrink UIElement to necessities by extending GameObject