Added Contact:getFixtures and Body:getContactList (see issue #905).

The list of Contacts associated with bodies changes during World:update (potentially multiple times), so you might miss collisions if you don't use the World callbacks at all.

src/modules/physics/box2d/Contact.h

@@ -148,6 +148,11 @@ public:
 
 	void getChildren(int &childA, int &childB);
 
+	/**
+	 * Gets the Fixtures associated with this Contact.
+	 **/
+	void getFixtures(Fixture *&fixtureA, Fixture *&fixtureB);
+
 private:
 
 	// The Box2D contact.