The new adjacent faces method border lookup fails in some directions around
45 degrees
* Use 8 Dijkstra directions (also diagonally) to determine which polygon is the
closest to each pixel. Using only Manhattan distance lead to large parts of
the texture which were matched with the wrong polygon.
* Use neighbroing polygons for edge search. The Adjacent Faces algorithm needs
to determine the closest edge, in UV space, each pixel. To speed this up
first as map is built which finds the closest polygon for each pixel along
horizontal, vertical and diagonal steps. Because this can sometimes be one
edge off we first look in the polygon from the map, if that fails also
check the edges of its neighbouring UV polygons.
Differential Revision: https://developer.blender.org/D13935
83fa6a1b2a