Bug#729289: transition: openscenegraph

["Rebecca N. Palmer" <r.palmer@bham.ac.uk>]

We have fixed versions of flightgear and fgrun, and I expect (but can't 
promise, I'm not the maintainer) that they will be uploaded soon.

If you want to remove libopenscenegraph80 and end this now, go ahead, 
it's uninstallable anyway (but note that a previous request (#737676) 
was rejected).