GUI: Soft Shadows in GUI
GUI: Full shadows on widgets
GRAPHICS: Make 32-bits rendering standard
SDL: Fixing up of artifacts in 32-bit mode
GRAPHICS: Fix BDF to work with 32bits
SDL: Making 32-bits rendering less hardcoded
SDL: 32bit cursor surface
GUI: Fixed offset of shadows
GUI: Fixing dark line present in shadows
GUI: Fixed shadows to look more like mockups
GRAPHICS: Fix VectorRendererSpec for RGBA8888.

Formerly values in the gradient and blending code overflowed and thus caused
incorrect colors. Now there's some special case for 32bpp modes, which needs
slightly more operations but assures a correct output.
GRAPHICS: Fix an assert that prevented rendering fonts in 4bpp
GUI: Added option for 32-bit rendering
SDL: Set BPP according to saved configuration
GUI: Force restart after changing rendering mode