already reached its scroll target. This keeps BS2 from using all available
CPU time all of the time.
It may still be that we need a mechanism for throttling the frame rate when
the scene is moving towards a scroll target, but my computer isn't really
fast enough to test that.
Two other bugs fixed in the process:
* I think the last frame of the render cycle was rendered, but not
displayed. If so, that should be fixed now.
* I discovered that there are cases where we do need to clear the screen
(e.g. at the "Meanwhile..." message when George has found out about the
Glease Gallery), so I've re-enabled the function and disabled it in the
render cycle.
svn-id: r9904
