New Nexus portal method; Shatterlock restructured

- Prisms no longer reset while on the ground.

- Due to constant griefing, the Nexus node has been given a new
alternative initiation. The spell Shatterlock can now manually open the
portal if the prism is used within the stonehenge.

- Shatterlock no longer functions with guild halls. Instead, it no
longer turns you orange, now has 1 hour base cast time, and will be used
to open (or force-start) many different kinds of events. The first event
of its kind is the alternative access to the Nexus node, not involving
tokens.

- The 1 hour base cast time can be drastically reduced by using 5 or
7-sided prisms, and by increasing caster spellpower.

    "The concentrated will of several Kraanan masters can be focused to "
      "force open dimensional barriers.  "
      "Requires Kriipa Claws to cast, and the casters' "
      "energies must be focused through a prism."

- Prism spells can no longer have their focus disrupted by anything
except resting, changing rooms, or running out of mana. This means
casters can fight to defend the prism. **Logging all the casters is the
only way for an enemy to break the spell.** That, or Mana Bombing
all of them ;p

These changes should help prism spells be an active and interesting
event rather than some mule nonsense. Also, the nexus node will
actually get done without a single griefer being able to annoy the
whole server in secret. Instead, they'll have to muster up some friends
and attack the shatterlocking group (and win).