Clean up body/RigidBody.java
Moved body/BodyIndexPair.java to collision/BodyIndexPair.java
Clean up constraint/ContactPointInfo.java
Clean up narrowphase/EPA/EPAAlgorithm.java and associated classes.
Clean up narrowphase/GJK/GJKAlgorithm.java and narrowphase/GJK/Simplex.java
Give contact points a color and disable depth checks during rendering of a contact point.