* flips the sprite ala MFE_VERTICALFLIP except you don't need to flip the direction of gravity for the object just to draw upside down
* stacks properly with reverse gravity
* FF_MIDDLESTARTCHANCE - has a 50% chance of starting the spr2 or FF_ANIMATE animation halfway in
* FF_SPR2ENDSTATE - if var1 == S_NULL, don't loop, just stop incrementing the frames. Otherwise, go to the state represented by var1.
The former is just something I did for fun, the latter is something that'll come in handy when porting in new-character-moves.
