remove Extras/obsolete/quickstep

improve serialization based on feedback: make it easier to serialize a single object, or single shape, or single bvh.
Modified Bullet/Demos/ConcaveDemo to use btSerializer to serialize the btOptimizedBvh (or optionally the trimesh+bvh)

You can also serialize trimesh without BVH, use:
serializer->setSerializationFlags(BT_SERIALIZE_NO_BVH);//	or BT_SERIALIZE_NO_TRIANGLEINFOMAP

src/BulletDynamics/Dynamics/btRigidBody.h

@@ -606,6 +606,8 @@ public:
 	///fills the dataBuffer and returns the struct name (and 0 on failure)
 	virtual	const char*	serialize(void* dataBuffer,  class btSerializer* serializer) const;
 
+	virtual void serializeSingleObject(class btSerializer* serializer) const;
+
 };
 
 //@todo add m_optionalMotionState and m_constraintRefs to btRigidBodyData