Celtpipe fixes & pipes use planes to their full extend.

Created by: PJB3005

Fixes a variety of bugs with celtpipes, can't be bothered to list them though.

Other things:

Pipes don't look derpy as crap anymore when layered and being partially hidden by floor tiles, vents now look fancy because their bezel is below the floors, even when the vent itself isn't.

New pipe layer manifold sprite, by @Skullyton, layer manifold now 100% supports celtpipes and looks sick:

Fixed unconnected pipe nodes not showing up on some things.

Made the layer adapter be coloured in the RPD, doesn't make its pipe item coloured though, nor fixes the horrible shading issues due to N3X15's sloth.