Feature request: Set PV module angle

[stheid]

When doing the PV calculation it would be interesting if one could configure the angle of the modules. particularly for facade PV or flat roof PV one would sometimes consider different angles than the area. I think that might not be super easy regarding shading, but it would be good to allow to user to play arround with it.

[FlorianK13]

This will be possible as soon as we merge #418