Directionality index calculation does not pass on balance argument to child functions

[dmalzl]

When calculating the directionality index using the cooltools.directionality.directionality function the balance argument is not passed on to the dirscore function it uses. This results in a KeyError when the 'balanced' column is not present in the pixels frame.

# function call
direcionality = directionality(coolerObj,
                               balance = False,
                               ignore_diags = ignore_diags,
                               window_bp = window,
                               min_dist_bad_bin = min_dist_bad_bin

calls dirscore without passing the balance argument:

dir_track = dirscore(
                chrom_pixels, chrom_bins, window=window_bins, ignore_diags=ignore_diags
            )