The requested changes have been implemented (including the addition of checkUnits()). This caught many more cases of incorrect units which have now also been fixed. As a result the list of packages affected has grown substantially. Jim Bosch, please check if all changes are satisfactory.

Note that CI (including ci_hsc) has completed successfully.

Looks fine to me. Tim Jenness made a good point about perhaps providing a bit more detail in the git commit message when the changes involve FITS headers, but if that's too hard to reproduce I'm not sure it's necessary; having looked a bit at the FITS files in question, I think the changes are sufficiently trivial that it's not too big a deal if we don't record them in detail.

I can easily rebase and reword when fits files were modified. But specifically mentioning which units were changed where would require a lot of work. I can however put the full list of possible replacements in. Although that might also be confusing.

Merge complete.