Actually load Fixture Lua functions

--HG--
branch : box2d-update

src/modules/physics/box2d/wrap_Physics.cpp

@@ -300,6 +300,7 @@ namespace box2d
 		luaopen_world,
 		luaopen_contact,
 		luaopen_body,
+		luaopen_fixture,
 		luaopen_shape,
 		luaopen_circleshape,
 		luaopen_polygonshape,

src/modules/physics/box2d/wrap_Physics.h

@@ -27,6 +27,7 @@
 #include "wrap_World.h"
 #include "wrap_Contact.h"
 #include "wrap_Body.h"
+#include "wrap_Fixture.h"
 #include "wrap_Shape.h"
 #include "wrap_CircleShape.h"
 #include "wrap_PolygonShape.h"