Ensure property tree is provided early to modellib. To disable: --prop:sim/rendering/cache=0 (enabled by default) (also requires simgear update)
This class has been removed in current OSG sources.
Move fgviewer code into fgfs binary. Its osgViewer-style main function is called from bootstrap.cxx if the --fgviewer argument is passed to fgfs. Use fgfs initialization functions in fgviewer codepath. Read command-line arguments and autosave.xml.
