Remove unused function create_mouse
Subpixel mouse movement

- Residual movement after rounding is stored
Better analog stick mouse deadzones and sensitivity

- A2R_DEADZONE could be even as low as 3 or 4, but I left some margin just to
  be safe
- 20 is way too much in any case in my opinion
- Small deadzone makes controlling the mouse a lot easier especially with the
  subpixel movement patch
Configurable analog mouse sensitivy and deadzone

- Options are mapping specific and can be changed with bindings
Merge pull request #21 from Ape/pullrequest/mouse_improvements

Mouse improvements