Better mouse support in free/dungeon cam

[slapjd]

Adds patches to the camera and input system to make the camera behave more like P5R Camera speed is directly controlled by the mouse movement amount per frame, instead of accelerating and decelerating slowly Mouse input for free cameras is taken directly from Windows Raw Input. In-game mouse sensitivity will no longer work so there's a configurable mouse input multiplier. In-game camera speed will still work though (but still applies to both mouse and gamepad). Controller inputs are detected and the fix is disabled for them. The entire patch set likely needs more extensive testing, so it's been put in the experimental section All of this should only apply to free cameras (i.e. inside Tartarus, the dorm lobby, etc.) and not cameras fixed in place (or battle cameras)

Fixes #31