StretchBlt: +clipping -bugs

StretchBlt: +clipping -bugs
- Additional checks (coordinates switched, NOOP, degenerate, outside of valid region, ...) and offset source rectangle in internal StretchBlt functions
- Fixes the StretchBlt problem in bug #3477, bug #3656 completely as well as bug #4089 and some issues reported elsewhere (bug #3325 for example)
- Increment horizontal position even if outside of the clipping rect (Evgeny Boltik, <BSTSoft AT narod DOT ru>)
- One small problem is left, one cookie for the person who reproduces it, two for the one that fixes it ;-)

svn path=/trunk/; revision=39483