correct exporing of loose edges, obj spec defines faces as needing at…

… least 3 verts (even though 2 vertex faces are in fact quite common).

now export these as lines.

io_scene_obj/export_obj.py

@@ -628,7 +628,7 @@ def findVertexGroupName(face, vWeightMap):
  if EXPORT_EDGES:
  for ed in edges:
  if ed.is_loose:
- fw('f %d %d\n' % (ed.vertices[0] + totverts, ed.vertices[1] + totverts))
+ fw('l %d %d\n' % (ed.vertices[0] + totverts, ed.vertices[1] + totverts))
 
  # Make the indices global rather then per mesh
  totverts += len(me_verts)