Fit beta-binomial parameters as DeCiFer option

Users can now pass an option to DeCiFer to use beta-binomial distributions to find clusters and assign mutations (default is binomial). We have updated the documentation to describe this procedure and the additional input file requirement containing the number of germline mutation counts in each sample.

In addition, we have also

1.) fixed a bug related to rescaling results by purity so that DCF/CCF values range from 0 to 1 for each sample, as opposed to ranging from 0 to the sample purity (as in v1*)

2.) changed the default number of restarts to 20 to make DeCiFer have decreased runtimes, we have noticed similar results with a wide range of restart values