Added plotter to plot 3D-embedded distance matrices; changed Rob-Foulds matrix in distance_matrix to always scale down to [0,1] interval, and always add noise; changed spectral_decomp in clustering options to prune=[estimate, -1 (all), n (int argument)] and local_scale [estimate (from binsearch_mask, same as prune), median (vector of row medians), -1 (all), n (int argument)]