add distance dependence tool to toolkit

[Thomas Gilgenast]

there exists a reasonably-generalized tool for plotting distance dependence curves across replicates, currently living on the cluster at

/project/jcreminslab/tgg_projects_2/luigi-pipelines-6/draw_distance_dependence.py

we should adopt this into lib5c as both a high-level plotter and a tool

[Thomas Gilgenast]

i think this was fixed in 1a24e47