histedit: replace @addhisteditaction with @action
@action supports verbs, messages, priority, and internal
messages should be translated.
internal means the action should not be listed.
geteditcomment will construct the verbs list based on
@actions (prefering priority over non priority, otherwise
favoring verbs with short forms over verbs without).
To run the tests, do:
cd tests/
python run-tests.py
See https://mercurial-scm.org/wiki/WritingTests for
more information on writing tests.