Add Error History function and config var. · 26b82202Kevin J. McCarthy authored
<error-history>, by default unbound, shows a list of the recent error messages displayed by Mutt via mutt_message() or mutt_error(). $error_history sets the size of the history ring. For now, I've decided to include mutt_message() messages too. If this is too chatty, we can restrict it to mutt_error() easily in the future.