Add love.physics.getDistance(fixtureA, fixtureB) - gets the distance between and the closest points of two fixtures

--HG--
branch : box2d-update

src/modules/physics/box2d/wrap_Physics.h

@@ -69,6 +69,7 @@ namespace box2d
 	int w_newWeldJoint(lua_State * L);
 	int w_newWheelJoint(lua_State * L);
 	int w_newRopeJoint(lua_State * L);
+	int w_getDistance(lua_State * L);
 	int w_setMeter(lua_State * L);
 	int w_getMeter(lua_State * L);
 	extern "C" LOVE_EXPORT int luaopen_love_physics(lua_State * L);