Organization?

#1214 raised an issue where there are now multiple JPL-provided services, raising the question of whether to host them under `jpl/` or `jpl_/`. I lean toward the former, but that is something new.

This issue prompted me to consider whether a broader reorganization might be useful. There are now several planetary/solar system modules, several line modules, and many more generic on-sky query modules. I think it would be convenient and helpful to have additional astroquery modules `astroquery/planetary`, `astroquery/sky`, `astroquery/lines`, etc. that would populate their namespaces with all relevant astroquery packages. These would be 'shortcut' subpackages meant to help people find the right tools more easily.

If we went with such a change, it would warrant a minor or major version number change.

Start by reading #1214 and inspecting the existing astroquery package layout. Compare the proposed astroquery/planetary, astroquery/sky, and astroquery/lines shortcut namespaces with the current module organization. Done would require an agreed reorganization plan and a decision on the corresponding version change.

Written by the indexing model from the issue text.