v2.0.0

This release corresponds to the 2.0 source code of Geert Jan van Oldenborgh's FF software from 1998.

Special thanks to the estate of Geert Jan van Oldenborgh (D.A. van Oldenborgh - Niels, E.D.D. van Oldenborgh, L.H. van Oldenborgh, I.B.S. van Oldenborgh.), who on 2024-12-06 generously licensed the software under MIT. (Signed license agreement document) Thanks also to G. J. van Oldenborgh's colleague Jos Vermaseren for coordination assistance with the licensing.