Classes
 ClassDescription
 Collision Stores information about collisions that occur in the simulation.
 IslandManager Tracks a list of islands.
 RapidBasic Like FlxBasic in Flixel
 RapidG A few useful Globals are stored here
 RapidGroup Group objects together, like FlxGroup
 RapidObject This class has LOTS of physics properties.
 RapidSim This is a top-level class that runs a rapid physics simulation.
 RapidText This class is a careful rip and downgrade of FlxText.
 RapidU 
 RapidWorld RapidWorld is like FlxState.
 Rlap Rapid Overlap This class contains a bunch of static functions to do hardcore Intersection Tests and Collision Resolution