-greatly improved accuracy in positioning between regular geometry and ortho
-added logic to find only full-screen rectangles and selectively scale them to remain full-screen at a wide resolution (works great for some games, needs improvement in others)
-replaced WidescreenStretchHUD option with WidescreenStretchBG, to toggle stretching as above
one pointer arithmetic one in TextureFilters.cpp (see tracker).
Once that is fixed Issue 24 in current form can be closed.
Testing done: Code compiles for normal and debug use without
any -Wall warnings and seems to yield the same results and previous
svn on my r300.