Beyond The End - The New End

Rework Jellyfish fight: phases, minion shield, tracking laser

Jellyfish boss
- Fix action selection: never pick the idle action or repeat the previous
  one; summoning depends on the number of alive minions.
- Laser now tracks the target during the charge and the beam at a limited
  speed (LASER_CHARGE_TRACK_SPEED / LASER_TRACK_SPEED). The laser sound
  follows the moving beam.
- Add fight phases at 66% and 33% health: shorter wait between actions,
  more minions allowed, bigger orb volleys and an extra volley during
  the beam in phase 3.
- Add a shield: the boss takes no damage while any minion is alive, with
  particle and sound feedback, and regenerates at 1/8 speed meanwhile.
- Regenerate outside the damage windows (configurable, 0.25%/s default).
- Scale health and damage with the number of players (configurable).
- Fire a ChargeFollowing volley when the target is out of stomp range.
- Set maxJumpCount on the server and never jump to the current platform.

Minions and projectiles
- Fix NormalProjectile hit detection: swept entity test and block
  collisions.
- ChargeFlash: no friendly fire, area explosion that does not break
  blocks.
- ChargeFollowing: 20 second lifetime.
- Minions always shoot when they have a target, die with the boss and
  reattach to it after a reload. Remove the vestigial random move goal
  and use getHurtSound for the hurt sound.
- Apply the player-count damage scale to minion projectiles.

Config
- Register a common config for the new Jellyfish options.