Also run test with Pytest....
Also run test with Pytest.
This now run many of the tests using pytest.
Many of previous pull-requests brought pytest compatibility; this now
actually would run a passing test suite.
This does not mean we can drop nose; in particular we still have plugins
fro doctests using iptest; which pytest does not run;
and we are still limited to pytest 3 (pytest 4 does not support
yield-test anymore)
There is thus still much work to do.