Support for multiple lids

[raphael-isvelin]

Note if you're reading: I don't have a big need for it for now and might not for a while: if you do, feel free to comment on the issue.

While Enclosure's constructor takes lid_on_faces: List[Face], it throws if it's anything other than [Face.BOTTOM].

Allowing to have multiple lids could be convenient in some cases. Would need to have a way to move the screw away from the corners, so they don't collide.

First step: #2.