Make tilt-angle optimizatation

[JanMaartenvanDoorn]

WHAT: For the new radian feature a tilt angle is needed, it is now configured at 34 degrees. This however might not be the optimal angle. Build in functionality that optimizes the angle, based on correlation with the historical load.

HOW:

• Before adding the GTI, first optimize the tilt angle.
• Add the GTI with the best angle as a feature
• Check if we can do the same thin for the azimuth
• add unit tests

TEST:

• Tilt angle is optimized when adding GTI as a feature