Develop migrations for 18.{6, 7} etc module renamings

[sweeneytr]

18.06 and 18.07 (and potentially other patches) rename many module names used in fits. Rather than being fixed ad-hoc as folks update fits that are broken, a set of regex rules or something similar could be used to update the entire site. These might want to be checked in, or not, but I'd be interested in helping if the maintainers had an opinion on how it should be handled.

[ayust]

If you can get a list of all the the changes (e.g. in Before,After line format) it's relatively straightforward to apply those across every file via something like sed. Most of the work is just getting the set of changes in an easily parseable format.