Added initial broadphase support for softbody versus softbody and softbody versus rigidbody (see btSoftSoftCollisionAlgorithm and btSoftRididCollisionAlgorithm)

Added 	SOFTBODY_SHAPE_PROXYTYPE.
Some refactoring for btSoftBody, needs more work.

src/BulletCollision/BroadphaseCollision/btBroadphaseProxy.h

@@ -59,6 +59,8 @@ CONCAVE_SHAPES_END_HERE,
 
 	COMPOUND_SHAPE_PROXYTYPE,
 
+	SOFTBODY_SHAPE_PROXYTYPE,
+
 	MAX_BROADPHASE_COLLISION_TYPES
 };