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.
