Checking for initialisation of FBO extension in Delete and Release as the dtor of FBO might get called even if the user did not initialise the required extensions.
Checking for initialisation of FBO extension in Delete and Release as the dtor of FBO might get called even if the user did not initialise the required extensions.

git-svn-id: 285d6e11b92f44d073a8e12a14e649675b16fc71@346 3ec011a9-ccf5-4689-8f2f-5f4aa021d377

UniStuttgart-VISUS/megamol,UniStuttgart-VISUS/megamol,UniStuttgart-VISUS/megamol,UniStuttgart-VISUS/megamol,UniStuttgart-VISUS/megamol