Finish making powerups drop out of bonus blocks when hit with butt-jump

Finish making powerups drop out of bonus blocks when hit with butt-jump
Allows bonus_blocks to drop contents when opened with a butt-jump.  This makes obtaining powerups while big less-trivial.  Note that bonus_blocks on the ground will still send their contents up (with the exception of the Tux doll).
There is some room for improvement here: a sort of "drop riser" would make it look nicer, and currently dolls are unobtainable on butt-jump which might be a little to harsh.