Fix (needs more testing) in btRigidBody::setCenterOfMassTransform, assign m_interpolationWorldTransform = xform; instead of m_worldTransform;

Thanks Jay for reporting
Added braking capability to btRaycastVehicle, see Bullet/Demos/VehicleDemo/VehicleDemo.cpp
Added glutKeyboardUpFunc, for vehicle demo (keep accelerating/breaking, until key released/UP). Hope this is compatible with most GLUT implementations.

Demos/VehicleDemo/VehicleDemo.h

@@ -51,6 +51,8 @@ class VehicleDemo : public DemoApplication
 
 	virtual void specialKeyboard(int key, int x, int y);
 
+	virtual void specialKeyboardUp(int key, int x, int y);
+
 	void renderme();
 
 	void setupPhysics();