rewrote quad buffer handling; dng requires explicit -S or --stereo flag to try...

rewrote quad buffer handling; dng requires explicit -S or --stereo flag to try and allocate stereo visual; if successful, stereo mode 1 will work without explicit switching of glformat in qwidget (which was broken and deprecated)
mapped glcanvas ctrl-0 to shadow toggling and ctrl-9 to ambient occlusion toggling
fused interlaced and quad based stereo to nearly the same code (2 lines different), incorporating deferred shading into both stereo modes
added experimental ambient occlusion algorithms; added experimental ambient occlusion quality
added shadow map weighting
renamed GfxObjBase::Outline and GfxObjBase::AALines to SetOutline and SetAALines, resp




git-svn-id: https://dng.biozentrum.unibas.ch/svn/openstructure/branches/new_gfx@2247 5a81b35b-ba03-0410-adc8-b2c5c5119f08