Prerelease of flasc as it turns public-facing

This is the first public release of the flasc repository, in conjunction with the beta release of floris v3.0 and two related articles:

1. B.M. Doekemeijer, E. Simley, P. A. Fleming. Comparison of the Gaussian Wind Farm Model with Historical Data of Three Offshore Wind Farms. Energies Special Issue: Fast-Running Engineering Models of Wind Farm Flows 2022, in preparation.
2. Bay et al., 2022, in preparation, article detailed to be announced.

Note that this prerelease of the flasc repository still relies on floris v2.4. More documentation to follow.