f4: after updating sources and adding new features, test compatibility with old behavior

[Maciej Komosinski]

Compile new and old f4 sources, test all sample f4 genotypes from docs and see how their corresponding f0 differs (it should not).

Also test sequences of mutations and crossovers for days using valgrind or another similar tool(s). Introduce unit tests if needed - where you feel the source is tricky or very complex.