WINTERMUTE: bailout = false by default

Quick profiling seems to show that *only* blitting is of any relevance here
WINTERMUTE: Debug assertion - make sure we never enter getFallback.
WINTERMUTE: Print warning if too many rects

(Should never happen in real world usage unless bug)
WINTERMUTE: Dirty rects are on by default.

Thanks to wjp's patches and overall improvements there is no particular
convenience in skipping dirty rects; overflow (=bug) is still an issue though
WINTERMUTE: Debug assertions
WINTERMUTE: Remove unused constants