Blessings on Monster Kills

In classic MUD style, players will pray over monster corpses they've
just killed and perhaps receive a blessing. These blessings default to
generic buffs like Bless, Magic Shield, and Super Strength, but can be
customized per monster. For example, Avar Chieftains also give Eagle
Eyes.

Players may also receive one short duration Area Enchantment at a time.
Multiple players killing monsters in the same room can have one each,
thus encouraging players to work together. Mules that are not killing
monsters do not contribute.

In this way, I believe we can cut out the need for players to bring a
second character to buff themselves. It's also pretty fun and breaks up
the monotony.

Spellpower for the buffs is 25 - 75, so it can be better to cast your
own buffs on yourself. Spellpower for the AEs is a little higher and
more consistent, since you only get one at a time per player.

Commit also includes some structural work on Jala to make caster-less
songs possible (the room is considered the caster) and to make sure that
multiple Jala songs work at the same time.