Introduced btActionInterface. This makes it easier to extend user-defined actions, such as vehicles and characters.

btRaycastVehicle and btKinematicCharacterController are derived from btActionInterface now.
Some cosmetic cleanup: changed sourceforce/sf.net url to bulletphysics.com.

src/BulletDynamics/Character/btCharacterControllerInterface.h

@@ -17,12 +17,13 @@ subject to the following restrictions:
 #define CHARACTER_CONTROLLER_INTERFACE_H
 
 #include "LinearMath/btVector3.h"
+#include "BulletDynamics/Dynamics/btActionInterface.h"
 
 class btCollisionShape;
 class btRigidBody;
 class btCollisionWorld;
 
-class btCharacterControllerInterface
+class btCharacterControllerInterface : public btActionInterface
 {
 public:
 	btCharacterControllerInterface () {};