Fixed some bugs about pixel-rounding…

I’ve discovered and fixed some bugs about pixel-rounding implementation. In some cases, the scrolling and the Y position of the player-sprite on the mobile-platforms was colliding and generating some glitches (the sprite is not correctly displayed, or flicks when the ramp goes up). I’ve corrected this and some minor issues about the control system.

Link to the demo:

http://pinellos.com/sandbox/plat_05/