From Marc Helbling, "please find the mergeTriangleStrip code merged in osgUtil::TriStripVisitor.
I've removed the references to DrawArrays as we should no longer produce any.

Note that:
* as the name suggest, it only works for triangle strips but could probably be easily extended to quads
* the resulting primitive is not highly optimized; we could probably sort the strips in order to minimize the number of primitive restart
* as we may merge DrawElementsUInt and DrawElementUShort, the code will only generate DrawElementsUInt"


git-svn-id: http://svn.openscenegraph.org/osg/OpenSceneGraph/trunk@14602 16af8721-9629-0410-8352-f15c8da7e697