Issue 172: raise error about missing AVbin in soundspace example.
Issue 172: raise error about missing AVbin in soundspace example.

kmonsoor/pyglet,odyaka341/pyglet,mpasternak/pyglet-fix-issue-552,mpasternak/pyglet-fix-issue-518-522,mpasternak/pyglet-fix-issue-518-522,Austin503/pyglet,kmonsoor/pyglet,mpasternak/michaldtz-fixes-518-522,shaileshgoogler/pyglet,cledio66/pyglet,Austin503/pyglet,kmonsoor/pyglet,Austin503/pyglet,qbektrix/pyglet,arifgursel/pyglet,odyaka341/pyglet,gdkar/pyglet,arifgursel/pyglet,qbektrix/pyglet,mpasternak/michaldtz-fixes-518-522,Alwnikrotikz/pyglet,odyaka341/pyglet,mpasternak/pyglet-fix-issue-518-522,xshotD/pyglet,odyaka341/pyglet,gdkar/pyglet,mpasternak/michaldtz-fixes-518-522,Alwnikrotikz/pyglet,shaileshgoogler/pyglet,xshotD/pyglet,google-code-export/pyglet,Alwnikrotikz/pyglet,cledio66/pyglet,qbektrix/pyglet,Alwnikrotikz/pyglet,mpasternak/michaldtz-fix-552,shaileshgoogler/pyglet,Austin503/pyglet,gdkar/pyglet,xshotD/pyglet,arifgursel/pyglet,qbektrix/pyglet,shaileshgoogler/pyglet,Alwnikrotikz/pyglet,mpasternak/michaldtz-fix-552,qbektrix/pyglet,cledio66/pyglet,mpasternak/michaldtz-fix-552,gdkar/pyglet,arifgursel/pyglet,kmonsoor/pyglet,mpasternak/pyglet-fix-issue-518-522,mpasternak/pyglet-fix-issue-552,mpasternak/michaldtz-fixes-518-522,odyaka341/pyglet,xshotD/pyglet,arifgursel/pyglet,google-code-export/pyglet,cledio66/pyglet,xshotD/pyglet,google-code-export/pyglet,mpasternak/pyglet-fix-issue-552,google-code-export/pyglet,shaileshgoogler/pyglet,google-code-export/pyglet,kmonsoor/pyglet,cledio66/pyglet,Austin503/pyglet,mpasternak/pyglet-fix-issue-552,gdkar/pyglet,mpasternak/michaldtz-fix-552