[WIN32K]

[WIN32K]
     - Correctly use the Clip, Meta, Rao, API and Vis Regions in DCs
     - Update the DC clipping object on demand each time a blt is performed
     - Reduce the number of region allocated with handles when it's not needed
This commit fixes numerous bugs regarding clipping, most notably SetDIBitsToDevice overlapping foreground windows
CORE-8353 #resolve #comment There are still a few quirks in winetests which will get fixed in a next commit
CORE-7628 #comment should be fixed in rev 63731, please confirm.

svn path=/trunk/; revision=63731