DrawState: Coding style cleanup
ClipToPicture test: Start the interesting test.

 * Also fix the compare graphics to what they are actually supposed to look
   for the nested states test.
ServerPicture: Set correct pen location after DrawString()
AlphaMasks: Use correct DrawState when playing picture

The current drawing state when the picture starts playing is the base
state that drawing commands in the picture itself should not be able to
modify. In the ClipToPicture test, the nested state test now at least
draws the last picture at the correctly scaled location.
OffscreenDrawingContext: Implement ResyncDrawState()

This is called whenever the DrawState is modified, so that it gets applied
to the DrawingEngine. Otherwise, the DrawingEngine works with an out-dated
state.
ClipToPicture: Correct the scaled clipping tests.