remove btContinuousDynamicsWorld, it is obsolete and was never completed.

If you need tunneling prevention, one option is to use the CCD motion clamping in btDiscreteDynamicsWorld. See also Bullet/Demos/CcdPhysicsDemo.
You can use an embedded sphere that prevents tunneling, using the following settings:

		body->setCcdMotionThreshold(0.5);
		body->setCcdSweptSphereRadius(0.9f);


Add a camera zoom setting for the demos, thanks to ejtttje, fixes Issue 543

Demos/OpenGL/DemoApplication.h

@@ -78,6 +78,7 @@ protected:
 	float m_scaleFactor;
 	btVector3 m_cameraUp;
 	int	m_forwardAxis;
+	float m_zoomStepSize;
 
 	int m_glutScreenWidth;
 	int m_glutScreenHeight;