hats vs helms

Something from <Someone>'s list:  some messages have hardcoded references
to "helmet" which sound strange when the character is wearing a hat or cap.
helm_simple_name() is comparable to the existing cloak_simple_name().  It
returns "helm" or "hat" depending upon whether the helmet provides the
same protection that yields the assorted repetitions of "fortunately,
you are wearing a hard helmet".  This choice ends up categorizing elven
leather helm as a hat (which I think is ok given that its undiscovered
description is "leather hat"), contrary to <Someone>'s suggestion that the
distinction be made based on whether the helmet was made of cloth.

     I started on this a year and a half ago but didn't commit it.
Unfortunately I don't remember why and haven't done any significant
additional work now--just recovered from some intervening bit rot and
confirmed that the patch as is seems to be working ok (in the trunk; the
branch side has not been tested).  I suspect that I meant to look for
additional helmet messages which could benefit from conditional headgear
description.  (Those "hard helmet" ones don't need it, although they
should perhaps be moved into a common routine instead of being replicated.)

src/hack.c

@@ -1,4 +1,4 @@
-/*	SCCS Id: @(#)hack.c	3.4	2004/08/16	*/
+/*	SCCS Id: @(#)hack.c	3.4	2004/11/11	*/
 /* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
 /* NetHack may be freely redistributed.  See license for details. */
 
@@ -1626,7 +1626,8 @@ stillinwater:;
 			if(mtmp->mtame) /* jumps to greet you, not attack */
 			    ;
 			else if(uarmh && is_metallic(uarmh))
-			    pline("Its blow glances off your helmet.");
+			    pline("Its blow glances off your %s.",
+				  helm_simple_name(uarmh));
 			else if (u.uac + 3 <= rnd(20))
 			    You("are almost hit by %s!",
 				x_monnam(mtmp, ARTICLE_A, "falling", 0, TRUE));