A number of significant changes have happened since the last commit:

1) the sampling fraction omega is a keyword argument throughout
2) keyword arguments are used for most inits of super classes
3) the fitness grid to integrate the polarizers has been made
asymmetric allowing for more a wider range for ancestor fitness compared
to child fitness
4) the tree length polarizer was added to the fitness inference. This
resulted in the addition of a number additional scripts to run, analyze
and draw the results from the polarizer analysis.