assassin droids; saber system

- assassin droids can fire with shields up now
- fixed causing assassin droids to never lower shields

- saber system mods work now toggleable by g_saberNewCombat
- g_saberLocksEnabled now allows you to disable saber locks (more for
testing purposes)
- bugs:
saber locks are very infrequent, special attacks don't work correctly in
the new system yet