Revert cycles to repeat starting node at the end.
Slight speedup in simple_cycles.  Order differs from recursive now.

Popping nodes from the end instead of beginning gives a different order,
but still valid.  Cycles now are a cyclic permutation of those reported
by recursive routine.  This revealed holes in tests that are fixed here.
Merge branch 'pr/890'

* pr/890:
  Slight speedup in simple_cycles.  Order differs from recursive now.
  Revert cycles to repeat starting node at the end.