added localepurge hook
NOTE: Remove trigger is probably not needed.
Using localepurge is not a good idea. NoExtract should be used to prevent extraneous locales from being installed in the first place.
@andrewgregory I did not know about NoExtract. Still, globbing would also become pretty messy if you want to keep more languages than just English (as in my case and I'm sure many others). I would still suggest adding this hook, since I'm sure some people wouldn't mind a few warnings when installing a package as long as all unnecessary locales are taken care of automatically (besides, commenting out CheckSpace apparently takes care of that issue as well).
Maybe I can add a comment inside the hook itself with a warning pointing to the url that you provided?