Ships improved

Minor improvements across the code.

Ship class now has a "breakOff" method for dismemberment.
ShipManager created to handle multiple ships, ship setup, and
encapsulate some of the complexity necessary for future navigation
upgrades.
StoryEvent upgraded to handle arbitrary optional data via hashmap.
AnimatorManager removed, references in Story removed.

Main program now spawns several ships at random, which all chase the
cursor. Push SPACE to make them explode (only one explosion can occur at
a time).