Add FLORIS based wind-speed estimator to FLASC

[paulf81]

Add FLORIS based wind-speed estimator to FLASC

Feature or improvement description
This PR adds a wind speed estimator based on measured power, and the expected power curve in FLORIS, to estimate the wind speed. The approach is modeled on the estimator based on data in @aclerc 's wind-up, in which the estimator blends between using power in the wind-ranges where power can be mapped to wind speed (below rated and above cut-in), and blends to using wind speed outside that range. The difference is that the power curve is taken directly from FLORIS. This approach will be useful when using FLASC to model-fit FLORIS, by ensuring that wind speeds can be selected which exactly reproduce the observed power, reducing a "noise" source of error unrelated to wakes.

Impacted areas of the software
floris_tools.py

Todo:

• Remove temporary example, included just to help review
• Add tests