Improves SpriteTest.
It is easier to see if Sprite works as SpriteBatchNode (and vice-versa).
Needed for the new renderer.
Also adds `const` to title() and subtitle()
Base class displays the Menu( <- O -> )
Improved in some tests the way to create entries.
Instead of defining the tests twice: the "create" method, and the entry
in the array, it is only needed in the array (ActionsTest, SpriteTest
and Texture2DTest)