Add option for maximum parsimony ancestral reconstruction

[zenalapp]

Example of how to do this here (might want to check other sources as well):
https://www.r-phylo.org/wiki/HowTo/Ancestral_State_Reconstruction

Because sometimes maximum likelihood gives weird reconstructions that we wouldn't expect given our knowledge of the phenotype. Possibly useful for genotype as well.

Might be worth discussing whether to have the choice to mix and match parsimony and likelihood for phenotype and genotype reconstructions as well (e.g. parsimony for phenotype and likelihood for genotype).