* Fixed a bug that made the scene always zoom out after zooming in & out quickly
* Zoom in/out in scene is limited
* Changed cube's initial rotation (now it looks better)
* Mouse control changes: left button rotates, right button moves and mouse wheel zooms (before, the middle button moved the scene and could be hit when zooming)
* Using constants instead of "magic numbers"
* normalizeAngle behaviour is now OK
* Deleted unused code
* Renamed some functions so it's purpose is clearer

Signed-off-by: Jose Luis Múgica <jlmugica@signalsoftware.es>