Added "delay" meta-skill to Pack skills and added Cooldown attribute to Pack skills

Added "delay" meta-skill to Pack skills, and added Cooldown attribute to pack skills. Together these allow for recursive, time-based abilities.

Cooldown is in seconds, delay is in ticks.

Example usage-

Roar:
  Cooldown: 10
  Skills:
  - msg 50:'&4$boss Roar!' >0 1
  - delay 60
  - msg 50:'&4$boss ROAR!' >0 1
  - delay 60
  - msg 50:'&4$boss ROAARRR!' >0 1
  - delay 80
  - pack Roar >0 1