Point selection 2d

Can now track a point on the 2D slice on the 3D plane.

It doesn't work for all angles, the calculated point is somehow not on the plane, but it works perfectly at the prinicipal axis.

Also guards against an infinite loop I encountered. If it does happen the plane calculations will be weird, but it should look okay. I don't know the conditions for the loop, so I can't check what it looks like after the kind of hacky fix.