Updates to genotype results column in the out.maf file

[andurill]

The n_ref_count and n_alt_count are never populated. My suggestion is to remove these two columns and provide an optional argument to enable counting "N" bases towards select genotype feature type.

Please refer to the table below:
1.) Red - columns that are proposed to be removed.
2.) Green - new proposed columns.
3.) Columns with the comment "optional argument to count "N" are the ones to which "N" base counts should be added if the optional argument is set by the user.