Joystick key rebinding support

[sergystepanov]

emmm, is it possible to support joystick rebinding in the future? i need it..

Originally posted by @xxxsen in #338 (comment)

[sergystepanov]

Will require a separate rebinding controller & possible Gamepad API support.

[MafiaInc]

This project is great! ❤️ I couldn't find anywhere such a fast and straight forward way of playing favorite retro games multiplayer with a friend (by just sharing an URL). Gamepad support would make it much much better as most of the retro games are used to be played with joystick/gamepad and this is the way most people prefer playing them.