* Fixed Issue #38: Made common GLSL header conform to the standards (no samplers in structs)
 * Fixed failing destruction of OpenGL buffers when destructing GeometryData from threads without OpenGL context
 * Fixed wrong pointers in GLContexts due to using this pointer of incompletely constructed class

git-svn-id: https://camplinux.in.tum.de/svn/campvis/trunk@463 bb408c1c-ae56-11e1-83d9-df6b3e0c105e