linewidth should be 0 in plotting.degradation_summary_plots

[mdeceglie]

rdtools.plotting.degradation_summary_plots() uses a matplotlib scatter plot with semi transparent points. The line width (lw) should be set to 0 to avoid undesirable solid lines appearing in the markers.

[mdeceglie]

Workaround until this is addressed:

ax1, ax2 = fig.get_axes()
ax1.collections[0].set_linewidth(0)