Installs the mouse handler.
Returns a value describing the motion along the X axis of the mouse since the last call to update().
The return value is from 0 to +/- 63, where positive values indicate movement to the right.
Like getXAxis(), but for up/down movement. Down is positive.
Returns true if mouse button 1 is depressed.
Returns true if mouse button 2 is depressed.
Resets the X and Y axis values to 0. These will then change as the mouse is moved.