wxflow updates

[RussTreadon-NOAA]

Testing of g-w PR #2654 identified

• the need to remove a wxflow hack from select modules, and
• add wxflow to the PYTHONPATH for the aero genyaml ctest

This PR brings these changes into develop

Resolves #1186

[RussTreadon-NOAA]

@DavidNew-NOAA - when you have time would you please review this PR? This PR enables the changes in g-w PR #2654 to be fully functional.

[RussTreadon-NOAA]

Thank you @DavidNew-NOAA for your review and approval.

@CoryMartin-NOAA , are you OK with the test/aero/genyaml_3dvar.sh changes in this PR?