Refactored forward rasterizer:

* Fixed Program passing incorrect vector in set_light_uniforms.
* Improved program handling of missing uniforms by warning.
* Reimplemented texture_shadeless program.
* Renamed variable ambColor to horizonColor.
Refactored forward rasterizer:

* Changed it to not render the scene if there are no objects to
  draw.
* Changed it to check program for every object rather than only
  last object.
Refactored rasterizer predraw methods, and object and camera
predraw methods:

* Fixed calling predraw twice.
* Fixed motioncam delay during object grabbing.