Rework how inset adjacency is determined.
Rework how inset adjacency is determined.

It was using the relative areas of the inset polygons but that wasn't reliable so now it's
explicitly checking to see if any points in the inset polygons are closer than a threshold distance.

ROBO3D/CuraEngine,ROBO3D/CuraEngine,alephobjects/CuraEngine,alephobjects/CuraEngine,ROBO3D/CuraEngine,Ultimaker/CuraEngine,Ultimaker/CuraEngine,alephobjects/CuraEngine