Classes
 ClassDescription
 AbstractCollection The abstract base class for all grouping classes.
 AbstractConstraint The abstract base class for all constraints.
 AbstractItem The base class for all constraints and particles
 AbstractParticle The abstract base class for all particles.
 APEngine The main engine class.
 CircleParticle A circle shaped particle.
 Composite The Composite class can contain Particles, and Constraints.
 Group The Group class can contain Particles, Constraints, and Composites.
 RectangleParticle A rectangular shaped particle.
 SpringConstraint A Spring-like constraint that connects two particles
 Vector 
 WheelParticle A particle that simulates the behavior of a wheel