Support for MANY controllers, now!

Before this upgrade, only the MSI GC20 V2 game controller was supported. Now I implemented a generic layout valid for every game controller recognized by SDL (a library that handles input).

The list of supported game controllers is here:

https://github.com/godotengine/godot/blob/master/core/input/gamecontrollerdb.txt

At the moment, the GC20 controller is out of list. I had to embed its configuration inside the game itself. So GC20 users can continue to play Ninja Vs. Robots!