1. TGLViewer performs internal loop on pad-primitives.
2. Timur: generalization of gl-plot-painters to allow external access.
3. Support usage of gl-plot-painters in gl-viewer.
4. Provide a default gl-sharing context for resource optimization.


git-svn-id: http://root.cern.ch/svn/root/trunk@19153 27541ba8-7e3a-0410-8455-c3a389f83636