Further cleanup of indxpath logic related to IndexOptInfo.opfamily array.

Further cleanup of indxpath logic related to IndexOptInfo.opfamily array.

We no longer need the terminating zero entry in opfamily[], so get rid of
it.  Also replace assorted ad-hoc looping logic with simple for and foreach
constructs.  This code is now noticeably more readable than it was an hour
ago; credit to Robert for seeing that it could be simplified.