[SE]add setting for movement sensitivity

[Fractalbase]

the settings contain a sensitivity setting for "look", which maps to either movement of the mouse, or the right stick on the gamepad.

however, there doesn't seem to be a sensitivity setting for "move", which in one way doesn't make sense if you're playing with mouse and keyboard, as the WASD buttons have no variability to them.

however, on a gamepad, "move" is handled from the left stick, which *does* have variability.

seems like adding a sensitivity setting for "move" would be a good idea.

thanks for reading.