[IDEA] Box2D Update

[Floog98]

In the original Box2D extension there is "enable for (this polygon v) mode (normal v) :: #57ba8f" this is used for having sprites like a level so the player can go down and up blocks in 1 costume but it is not in the remake and it is one of the most useful parts of this extension.

[CST1229]

this was removed because it was buggy and also broken by later Scratch changes