GitLab

 * introduced abstract tgt::GLContext for thread-safe management of an OpenGL context
 * introduced Qt-threading based tgt::QtGLContext, tgt::QtThreadedCanvas and tgt::QtThreadedPainter
 * adapted tumvis-core and tumvis-application to new OpenGL context handling

git-svn-id: https://camplinux.in.tum.de/svn/campvis/trunk@194 bb408c1c-ae56-11e1-83d9-df6b3e0c105e