Unsimplify alias precedence handling
Unsimplify alias precedence handling

As discussed with hoellen on matrix, since postfix indeed supports including
the recipient delimiter character in a verbatim alias, we should support so too
— and handle its precedence correctly. The clearer and simpler formulation of
the precedence-clauses are credit to @hoellen. Thanks!

kaiyou/freeposte.io,kaiyou/freeposte.io,kaiyou/freeposte.io,kaiyou/freeposte.io