Issue https://github.com/OpenACalendar/OpenACalendar-Web-Core/issues/253 - must make sure uncancel and undelete actually does that
Issue https://github.com/OpenACalendar/OpenACalendar-Web-Core/issues/253 - make clear in event history what "restored!" means
Issue https://github.com/OpenACalendar/OpenACalendar-Web-Core/issues/253 - show cancelled history in emails