Handle corner nodes separately from the rest of the fitted nodes.

Handle corner nodes separately from the rest of the fitted nodes.
Add fitted nodes in after corners and polygon nodes since the fitted nodes
  are less important.  Subsequent nodes will "snap" to previous nodes if
  they are "close enough."
Need to manually divide segments to prevent "T" intersetions which can
  confound the triangulator.  Hey, I got to use a recursive method!
Pass along correct triangle attributes to output file generator.
Do fine grained node snapping for corners and polygons, but course grain
  node snapping for fitted terrain nodes.