fill, then cull

[gordonwoodhull]

The "fill" ragged border resolution algorithm now works as designed - it fills any gaps where the missing rhomb has two neighbors that intersected the polygon, and one of the triangles of the missing rhomb also intersected.

It leaves a smaller % of border rhombs with two sides exposed than does "cull".

However, this algorithm can still leave rhombs with three edges exposed, so it should call "cull" when it completes.