added debug code to texture creation routine, in case of an error we now know exactly where things go wrong 
added debug code to texture creation routine, in case of an error we now know exactly where things go wrong 


git-svn-id: 83c4c97093aeea62ac982fbfd516bf9db27f5c99@1815 c36c8488-0289-0348-9b64-b301f74bd9a7

BlueBrain/Tuvok,BlueBrain/Tuvok,BlueBrain/Tuvok