Fix NumKeys bindings

This commit fixes hardcoded keybindings. Now:
- Num keys bindable independently from F1-F8 keys
- NumPad keys bindable independently from arrow keys
- NumPad numeric keys decimal codes (NumPad0 - NumPad9): 310 - 319

Example (keyconfig.plist):

	key_roll_left				= 314;		// NumPad4
	key_roll_right				= 316;		// NumPad6
	key_pitch_forward			= 318;		// NumPad8
	key_pitch_back				= 315;		// NumPad5
	key_yaw_left				= 317;		// NumPad7
	key_yaw_right				= 319;		// NumPad9