Three main changes:
1. Add four new ART headers for updating/deleting/adding options/flags to
the pathena command run for a job. The four headers are:
   art-pathena-options-add
   art-pathena-options-remove
   art-pathena-flags-add
   art-pathena-flags-remove
where options take a value and flags do not.

2. Refactor ArtGrid methods to focus either on single or batch jobs instead of given methods
doing both, and thus being quite long.

3. Fix art-include code so that non-globbed values match exactly. That is:
"art-include: master/Athena" will now only match master and not match other
branches that have master as a prefix.

Minor stuff:
1. Remove all __author__ references and move to a single AUTHORS.md file.
2. Update all copyright headers to 2023.
3. Moved all __version__ references in scripts to ART/__init__.py, so that
a single variable only has to be updated when a new tag is made.