Gamepad support, full gamepad control, and button rebinding

[jummy0]

The game should allow the use of a gamepad controller, and still be entirely functional. This will allow a customized play style, and allow use on gaming systems without a keyboard. This will be more important when the engine is shared with Speedy Blupi, as many people prefer using a gamepad for side-scrolling platformer games.

[Skywalker13]

Rebinding should be configurable in the config.json file for v1 and with a screen too for v2