[split] Teemu's Part Checker

[Roland Melkert]

"T-Junction detected." T-junction detection can be very difficult to implement and only a small minority of T-junctions are actual problems. Do we really want to automate this?

T-Junctions can cause seams during rendering so I would prefer them gone

Detecting them could be done by checking if vertices are near triangle/quad side lines without being part of that polygon.

This might need to include full recursive mesh data so it can check on the assembled part level.