reverted all changes to the gfx module since r2007, except map_iso downsampling

moved all these features to the new_gfx branch, including

cpk fast spheres
helix cylinders and flat beta strands
ambient occlusion
improved scene export and offscreen buffer handling
fixes to shaders
new GfxObj and GfxObjBase re-organization
backbone trace/spline re-write
vertex array fixes
multisample extension detection



git-svn-id: https://dng.biozentrum.unibas.ch/svn/openstructure/trunk@2130 5a81b35b-ba03-0410-adc8-b2c5c5119f08