added Engine::Object::setGravityMode()

git-svn-id: svn://anubis/anaglym/trunk@237 99a6e188-d820-4881-8870-2d33a10e2619

tests/managed_objects.lua

@@ -43,5 +43,8 @@ function key_down_event(key)
         init_obj(box)
         ag.createAMotor(0, box,
             { x = 0, y = 0, z = 1, vel = 10, fmax = 10 })
+        local x, y, z = box:getPosition()
+        box:setPosition(x, y, 2)
+        box:setGravityMode(false)
     end
 end