[MODDING] Add a callback that a allows to detect when a player press key X

[Khanx]

Add a callback like OnPlayerInputKey(Players.player, Key x)

This can be useful to send an interface to a player when he clicks X key.

[pipliz]

Added to #322 Is like 5-7 generic "mod function" keys for the key rebinding menu OK? I don't want to send a callback for literally every key the client presses, and the client will probably want to rebind it in some cases.