Updated box2d from 2.2.1 to 2.3.0

--HG--
branch : box2d-2.3

src/modules/physics/box2d/Physics.h

@@ -43,6 +43,7 @@
 #include "WeldJoint.h"
 #include "WheelJoint.h"
 #include "RopeJoint.h"
+#include "MotorJoint.h"
 
 namespace love
 {
@@ -250,6 +251,13 @@ public:
 	 **/
 	RopeJoint *newRopeJoint(Body *body1, Body *body2, float x1, float y1, float x2, float y2, float maxLength, bool collideConnected);
 
+	/**
+	 * Creates a new MotorJoint controlling the relative motion between body1
+	 * and body2.
+	 **/
+	MotorJoint *newMotorJoint(Body *body1, Body *body2);
+	MotorJoint *newMotorJoint(Body *body1, Body *body2, float correctionFactor);
+
 	/**
 	 * Creates a new Fixture attaching shape to body.
 	 * @param body The body to attach the Fixture to.