…riginal face

…triangualation (even when dim=3), it is important we give it a non degenrate face.. this commit checks which coordinates have the largest variance and rearanges the dimensions accordingly. this doesnt affect the model in anyway

…a triangulation

* Correct is2d detection: 2D only if all vertices are 2D,
  and treat 0 the same as an absent third coordinate.
* Always swap y and z coordinates when importing/exporting FOLD,
  independent of 2D status, for consistent behavior in all cases.
  (To get there, `rawFold` also has swapped coordiantes.)
* To decide `needsFlip`, instead of looking for a face edge in the first
  triangle, which can fail if the first triangle is a fully interior triangle,
  look for the first edge of the face in all the triangles.

Swapping y/z flips the coordinate system between left- and right-handed,
effectively reversing the notions of cw/ccw. This isn't an issue in 2D,
because there it would be the same as mapping (x, y, z) → (x, -z,
y) (because z=0) which doesn't flip handedness, but it's a problem in 3D.

… (because of it using only the first two coordinates, and possible degeneracies there). this update makes sure there are at least enough triangles before breaking

… 1, 2]