Sprite Shadows

Ports the OpenGL sprite shadows from 2.1, and also adds sprite shadows to software(they are more basic than the GL ones), they can be enabled with shadow sprite and to switch back to drop shadows, use shadow drop GL Spriteshadows Software Spriteshadows

added 1 commit

• 00e121b1 - Make GL spriteshadows behave more like their 2.1 counterparts(might make an option later)

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This doesn't seem to render right with Tails's shadow.

Not a showstopper, but we should leave the default be if this can't be fixed. Nevermind, this is already the default. I didn't notice that you renamed On to Drop.

merged manually