* Added tests for general functions, function and exe wrappers,
Morris Elementary Effects, SA test functions, screening, and tee
to increase coverage.
* Renamed ntsteps to nsteps in eee to be consistent with
screening/ee.
* Change check of logfile in eee: check for string rather than
file handle to be independent of Python version.
* Replaced kwarg.pop mechanism in exe wrappers because it removed
the keywords from subsequent function calls.