fix #H4436 - polyself message sequencing bug

fix #H4436 - polyself message sequencing bug

for digesting a swallowed critter.  The "you kill <critter>" message
was left implicit, but if hero gained a level, that made "welcome
to level N+1" look like it was issued out of sequence because it's
immediate and the "you totally digest <critter>" is delayed.  Giving
the you-kill-it message explicitly makes things be more verbose but
avoids having the new-level message seem out of order.