CPotree update to 2.0, output same as before

[m-schuetz]

Initially, CPotree should output the same data as previously.

This is how CPotree is currently in use:

• https://sitn.ne.ch/pytree/profile/get?minLOD=0%20%20%20%20%20%20&maxLOD=6&width=7&coordinates=%7b2537550,%201199179.69%7d,%7b2547350,%201199979.69%7d&pointCloud=sitn2016&attributes=
• https://github.com/sitn/pytree/blob/master/pytree/views.py#L49
• https://github.com/sitn/pytree