re-submission of previous large commit, with all files this time (PDB flags, atom index, etc)

some tinkering around with the offscreen rendering again, half stable only
added automatic centering on first GfxObj that is added to the scene
added temporary interface to the shader api until we have proper material params
added direct char param for python Residue.SetSecStructure (too many types can be evil, too)




git-svn-id: https://dng.biozentrum.unibas.ch/svn/openstructure/trunk@2067 5a81b35b-ba03-0410-adc8-b2c5c5119f08