action_auto_perf_cause names translatable for no reason
Hubert Kowalewski asked, at freeciv-i18n mailing list, about the context of action_auto_perf_cause names for being able to translate them in a sensible way. As I looked at it, it seems to me that they are not currently used at all (grep -r "action_auto_perf_cause_name" finds nothing). Depending on what are the future plans for them, either make them untranslatable to save translators' work and time, or clarify what kind of context they may appear.
I think this was a copy paste error. They should be untranslatable, at least for now.
Pushed to master and 3.1. I hadn't uploaded the 3.0 version.