Fisher geometric fitness model

[ThibaultLatrille]

Adding SimuGeo model (on top of SimuDiv, SimuPoly, SimuFold)
For each site of the protein, the 20 amino-acid are N-dimensional vectors (the vectors can be different for each site, or shared across the sequence).
The phenotype is a N-dimensional vector given by the sum at each site of the encoded amino-acid.
The fitness is given the Gaussian distribution of this N-dimensional vector.