Classes
 ClassDescription
 Bungee Bungee

A bungee will only exert a pulling force if the spring is extended further than its restlength

 MouseSpring Drags bodies with Mouse
 RigidBodyBungee Bungee attached to a point on a body TODO: comment
 RigidBodySpring Spring attached to a point on a body TODO: comment TODO: override clone TODO: override invert
 Spring Creates a spring force

Due to the need for spring forces to update within an ISimulatable's integration, there is 1 Spring element per force generation.