fix gamelog 1st kill vs 1st weapon hit sequencing

If the first monster the hero kills is killed by the hero's first hit
with a wielded weapon, report the hit first and kill second instead of
the other way around.  Not as hard to manage as I feared, but bound to
be more fragile than the simpler handling that produced the odd order.

Also while testing it I knocked something into a polymorph trap and it
changed form without any feedback.  Give foo-changes-into-bar message
if the hero is moving and can see it happening.  It isn't needed with
a monster moves deliberately into a polymorph trap but probably would
be useful when that's is unintentional.

The "<hero> enters the dungeon" log message had a trailing period but
other log messages don't have sentence punctuation, so take that off.

src/allmain.c

@@ -762,7 +762,7 @@ welcome(boolean new_game) /* false => restoring an old game */
 
     l_nhcore_call(new_game ? NHCORE_START_NEW_GAME : NHCORE_RESTORE_OLD_GAME);
     if (new_game)
-        livelog_printf(LL_MINORAC, "%s the%s entered the dungeon.",
+        livelog_printf(LL_MINORAC, "%s the%s entered the dungeon",
                        g.plname, buf);
 }