AE safety issues fixed, RE bugs fixed

Qorbane and Shalbane are now using Radius Enchantment safety code, as
old-style AEs similar to AMA, Winds, etc. This means they're now useable
in all conditions. They will apply to both guildmates and enemies. They
are both also now in a "Bane" subclass that will allow us to easily add
banes for any school if we need to. The caster of a Bane also gets
proper credit for a kill now.

Silence has been converted to RE with a 1 mana per second drain. It no
longer breaks Jala songs or prevents all casting. For the time being,
it only prevents communication in a large range around the caster. We
can't have a level 3 spell like this nuking all magic... if someone
thinks of a good use for it, that can be added later.

For now, it still remains unique in that it silences communications.
Perhaps enterprising fighters will use it to prevent calls for help from
victims.

Sandstorm will no longer multi-hit players who are under the effects
of multiple sandstorms. Only the strongest sandstorm will do damage.

The "change zones and get weird" bug with Radius Enchantments has
been fixed. It was caused by the game not knowing how to remove
one of two instances of the same spell with the same caster and
same spellpower. I fixed it by also tying them to the room of origin.
This bug was also the cause of Truce being weird.
This needs to be posted (as does the shalbane one) to prevent issues when casting focus spells.