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/trap.c

@@ -2129,7 +2129,12 @@ trapeffect_poly_trap(
         if (resists_magm(mtmp)) {
             shieldeff(mtmp->mx, mtmp->my);
         } else if (!resist(mtmp, WAND_CLASS, 0, NOTELL)) {
-            (void) newcham(mtmp, (struct permonst *) 0, FALSE, FALSE);
+            (void) newcham(mtmp, (struct permonst *) 0, FALSE,
+                           /* if hero is moving, he probably just swapped
+                              places with a pet or perhaps used a joust
+                              attack to push mtmp into the trap; describe
+                              mtmp's transformation into another shape */
+                           (!g.context.mon_moving && in_sight));
             if (in_sight)
                 seetrap(trap);
         }