Fix bug hiding aux variables (issue #43)

[LukeJones123]

Pull Request Checklist:

• [X ] This PR addresses an already opened issue (for bug fixes / features)

  • This PR fixes issue #43

• [x] Tests for the changes have been added (for bug fixes / features)

• [x] Documentation has been added / updated (for bug fixes / features)

• [x] HISTORY.rst has been updated (with summary of main changes)

• [ ] I have added my relevant user information to AUTHORS.md

• What kind of change does this PR introduce?: Bug fix

• Does this PR introduce a breaking change?:

• Other information:

[agstephens]

Hi @LukeJones123, this PR looks good. Thanks for spotting this bug. Could you please add a unit test, or modify an existing one, to verify that the aux variables are being correctly accessed. Then I will merge the PR.

[LukeJones123]

Hi Ag. I added a test to test_na_file.py. Running that revealed another bug actually, in getAuxVariable(), which I've also now fixed as part of this branch.

[agstephens]

@LukeJones123 Thanks for finding the bugs and adding fixes. I'm re-running the CI now.

[agstephens]

Hi @LukeJones123, tests are now passing which is great. Please can you update the HISTORY.rst file to note this change, and feel free to add yourself as an author to the AUTHORS.md (unless you'd rather remain anonymous - which is also fine :-)

[LukeJones123]

Hi Ag. The HISTORY.rst is formatted using version numbers and release dates. What values would you like me to use there?

[LukeJones123]

And do you want me to add a comment for the units-parsing feature branch too?

[agstephens]

Hi @LukeJones123, yes please.

[agstephens]

@LukeJones123, in the HISTORY.rst file, please add a section with the title: v2.0.2 (pending release) - and I'll create a new release when the current set of updates/fixes are merged. Thanks

[LukeJones123]

Hi Ag. I've done that now.

[agstephens]

Thanks @LukeJones123