Triangulate: Option for Longest Diagonal

There are times when blocking out terrain becomes... frustrating. The enclosed image is just one example of what can go wrong with current automated triangulation. Those hideous notches; they unsettle me.

If we could assign different vertex groups different methods of triangulation, and added a "Longest Diagonal" option to join its "Beauty" "Fixed" "Fixed Alternate" and "Shortest Diagonal" brethren things would be better.