Gamecontroller support

Added gamecontroller support.

A default config file is loaded that should work with most controllers so no setup should be required. However, you can customize the mappings by going to Left Sidebar -> Rc -> Game Controller Setup.
To actually control the copter, Connect -> Press Middle Button ("Control") -> Turn the switch in the center of the screen on -> Arm
The switch is only there as a precaution and will probably be removed if enough people test the code.

Also, someone will have to update the UI to make it look good and work on different screen sizes.

WARNING: I have only tested controlling the copter with no propellers so be careful!