Improving interface and help comments in single job analysis.

[ledm]

These jobs got bumped out of PR #34 :

• bgcval2_make_report.py
• bgcval_p2p.py
• bgcval.py (this used to be the whole package, but it needs to be framed in a clearer way.)
• Fix hard wired paths in download_from_mass.findLastFinishedYear

I'm going to be working on them in https://github.com/valeriupredoi/bgcval2/tree/improve_help_messages_singlejob, which is based on the branch in pr 34.

[valeriupredoi]

Excellent! can you merge main now in that branch pls? And open a PR asap so we don't start having ghost branches 😁 Also, we should now concern with tests as well - I have test_command_line.py now, so we'll have to add executables and tests for them there too, we're big boys now, with tests 😆

[ledm]

Good one. Already merged. I'm leaving tests up to you!