WINTERMUTE: Remove useless Rect extra argument from fadeToColor.

It is not used anywhere, and Mnemonic has confirmed that the original
engine does NOT support anything but full screen fades.
WINTERMUTE: Remove _tempDisableDirtyRects
WINTERMUTE: Add a DirtyRectContainer to generate multiple dirty rects
Merge branch 'wme_multirect' into wme_rendering

Conflicts:
	engines/wintermute/base/gfx/osystem/base_render_osystem.cpp
	engines/wintermute/base/gfx/osystem/base_render_osystem.h
WINTERMUTE: Properly clear wantsDraw if optimized is empty
WINTERMUTE: Fix one multi-rect intersection case