Externalize parsimonyCost, and modify extract function.
Document new functions in parsimonyNumber.
Correct enumerate_parsimony.
Ducumenting functions enumerate_parsimony.
Add some automatic testing with testthat.
Handle case only one cluster for cost computation (using aaply instead of apply).
Some other tests.
Handle the case where clusters numbers do not follow one another (enumerate_parsimony).
Colors and parameters to plot solutions.
Merge branch 'new_parsimonyNumber_bis' into develop