added initial billboard geometry shaders (untested)
rm ogre_media/materials/scriptsCompatibility
bugfixed billboard geometry shader
added geometry shader versions for sphere and square materials
billboard.geom: fixed wrong tex coords
added --opengl command line option
billboard.geom: fixed incorrect w component
moved nogp.program to nogp folder
Merge pull request #626 from ros-visualization/billboard-geom-shader

Billboard geom shader