* Cleaned up some loose ends with free tiles that are paged out of the cache.

* Cleaned up some loose ends with free tiles that are paged out of the cache.
* Finally I think I have the partial ssg tree deletion routine working correctly
  after I managed to break it (and other confusion in the code cause it to
  never be called so I didn't notice the problem.)
* Converted several SG_INFO statements to SG_DEBUG to clean up some
  extraneous console output.
* This *should* conclude my investigation into a massive memory leak. :-)