[#544] added a `insertContainer` function to the quadtTree (faster insertion) and added back recursion case with child containers

Not sure this would work properly though (as children position is
supposed to be relative to their parent container). It seems however
that this was the case before as well ?

https://github.com/melonjs/melonJS/blob/1.0.x/src/renderable/container.js#L557