ammendments by Robert Osfield, adding get/setSharedStateManager()
methods into osgDB::Registry, and clean up fixes in SharedStateManager
for the StateSet arrays.
this are replaced by the osg::computeLocalToWorld/WorldToLocal() functions
found in osg/Transform.
Made the ReleaseTextureAndDisplayListsVisitor a public nested class of
osgDB::DatabasePager to allow it to be used in the TXP plugin, and added
usage of this visitor to the TXP plugin to make sure that textures and
display lists are released during the update thread.
