merge javelin and spear skills (trunk only)

Part of "multi-shot throwing proposal" last January.  Unfortunately
some of the bits that I had implemented back then have vanished, so I'm
doing it over from scratch.  There were three main parts:
1) allow multi-shot volley throwing for all stackable weapons (affects
   knives, javelins, spears, and boomerangs; other weapons either don't
   stack or are already multi-shot);
2) make worm teeth and crysknives be stackable like ordinary knives;
3) merge spear and javelin skills, so that allocating skill points to
   their use becomes more attractive and they might get used more.
This patch only does #3.

     Since the monk skill set shrinks by more than any of the other roles,
I bumped max skill for escape spells (haste self, invisibility, jumping,
levitation, and teleport away) from basic to skilled; that's the only
skill adjustment included here.  For the couple of roles had different
max values for spear and javelin skill; this keeps the higher of the two.

src/weapon.c

@@ -1,4 +1,4 @@
-/*	SCCS Id: @(#)weapon.c	3.5	2006/07/08	*/
+/*	SCCS Id: @(#)weapon.c	3.5	2006/12/14	*/
 /* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
 /* NetHack may be freely redistributed.  See license for details. */
 
@@ -34,7 +34,7 @@ STATIC_VAR NEARDATA const short skill_names_indices[P_NUM_SKILLS] = {
 	TWO_HANDED_SWORD, SCIMITAR,       PN_SABER,     CLUB,
 	MACE,             MORNING_STAR,   FLAIL,
 	PN_HAMMER,        QUARTERSTAFF,   PN_POLEARMS,  SPEAR,
-	JAVELIN,          TRIDENT,        LANCE,        BOW,
+	TRIDENT,          LANCE,          BOW,
 	SLING,            CROSSBOW,       DART,
 	SHURIKEN,         BOOMERANG,      PN_WHIP,      UNICORN_HORN,
 	PN_ATTACK_SPELL,     PN_HEALING_SPELL,