API changes, small fixes, cleaning.

API:
+ setRotationQat
+ rotateQuat
+ getRotationQuat
- setTexturesMode
- getTexturesMode

Added a second variant to the rotation functions. The normal ones now
use Yaw-Pitch-Roll angles, and the Quat functions use a quaternion.

Removed the textures mode functionality in favor of a new white shader.

The normals and uvs shaders now affect also MDX models.