add test for the rectangle robot type

tests/test_dynamic_window_approach.py

@@ -17,7 +17,12 @@ class Test(TestCase):
         m.show_animation = False
         m.main(gx=1.0, gy=1.0)
 
+    def test2(self):
+        m.show_animation = False
+        m.main(gx=1.0, gy=1.0, robot_type='rectangle')
+
 
 if __name__ == '__main__':  # pragma: no cover
     test = Test()
     test.test1()
+    test.test2()