Reported by copperwater "on behalf of Maud": when hero hears an
unseen monster read a not-yet-discovered scroll of create monster
and doesn't see any new monster appear, the player is given a chance
to call the scroll something. When hearing an unseen monster read
a not-yet-discovered scroll of teleportation, the label is revealed
but no such 'call it' opportunity is offered, so the player could
deduce which of the two scroll types it was for either case.
Provide an opportunity to supply a 'called' name for scrolls of
teleportation when heard being read, same as with create monster.
Surprisingly complicated to achieve.
Eliminated a couple of goto's in the process.
Fixes#1046
7e4be52a6c