Make runtests.py a little more versatile: support -x, and arbitrary flags to be passed to regrtest.py.  Also add -h for help, and summarize the BAD/GOOD/SKIPPED files at the end.
Make runtests.py a little more versatile: support -x, and arbitrary flags
to be passed to regrtest.py.  Also add -h for help, and summarize the
BAD/GOOD/SKIPPED files at the end.

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator