Fixed, cleaned up and updated AbstractShaderProgram documentation.
Fixed, cleaned up and updated AbstractShaderProgram documentation.

DerThorsten/magnum,MiUishadow/magnum,MiUishadow/magnum,ashimidashajia/magnum,MiUishadow/magnum,MiUishadow/magnum,MiUishadow/magnum,ashimidashajia/magnum,DerThorsten/magnum,ashimidashajia/magnum,MiUishadow/magnum,DerThorsten/magnum,ashimidashajia/magnum,ashimidashajia/magnum,DerThorsten/magnum,DerThorsten/magnum