Triangulation issue: extra triangles in certain sectors

[jmickle66666666]

Examples:
DOOM2 MAP02 Sector 11
DOOM2 MAP03 Sector 15

An extra triangle is getting created in some sectors. This triangle is reversed, and will not be shown unless looking at the map from above or below. I'm putting it here as a minor issue as (I believe) it has no player impact on the generation of the level currently, but should be fixed.

[jmickle66666666]

I think this issue is breaking triangulation in some levels.

[jmickle66666666]

Latest commit has made the issue appear on Doom 2 MAP01 Sector 1

[jmickle66666666]

i think this has been fixed in my triangulation implementation