Overhaul MP system

MP is determined identically for enemies and party members. I don't see
that changing, so having a separate MP function for characters and
enemies just made the gamedef larger for no real gain.
Fix for Scenario slowdown

Stupid me, after the Scenario overhaul I forgot to remove the explicit
synchronize command in the run() method, originally meant to prevent the
camera and such from being reset until the rest of the scene was done.
Every time Scenario.run() was called, another synchronize command was
added to the end of the queue; after the scene is run enough times, this
causes massive delays while Scenario executes a series of useless
synchs.
Experimenting with cooldown formula

Cooldown time for moves is now based on rank^2. Not sure how this will
affect game balance, need to do some more testing first.  It did make
the RSB fight much more exciting, though!