SDL2 fix, SDL_Rect type
SDL2: fix colorkey usage
SDL2: fix SetPerSurfaceAlpha
SDL2: SDL_SetAlpha fixes
SDL2: fix SurfaceCopyScope: alpha handling
SDL2: fix SDL_SRCALPHA, alpha blend modes
SDL2: more fixes for SDL_SRCALPHA, alpha blend modes
small fix (Surface_getColorKey)
remove StaticAssert.h (static_assert). we'll use C++11
fix up static_assert usage (C++11)
CMake: enable C++11