game_engine. Remove ID field from UI pointer.

Remove UI field from ui pointer.
Remove id  access methods.
game_engine. Replace header includes in game with class predeclarations.
game_engine. Fixes to math quaternion.

Add quaternion convenience type.
Fix quaternion construction from rotation and axis vector.
game_engine. Implement ui pointer log stream operator.
game_engine. Modify touch handler to call game touch events.

Add game interface field to touch handler.
Change touch handler on_* methods to call the game interface on_touch_* methods.
game_engine. Change test game to rotate on touch.

Add ui prebuilt lib.
Add on touch event handling methods to test game.
Add rotation methods and fields to test game.