Fixed serious plotting issue caused by change in matplotlib v3.8.2. Released two new notebooks, detritalPy-mix and detritalPy-nmf, and associated code, that allow forward and inverse mixture modeling. Updated MDS routine to account for change in how stress is reported for non-metric MDS by sklearn.manifold.MDS. Added Wasserstein distance calculation (Lipp and Vermeesch, 2023: Geochronology). Other minor changes to detritalPy notebook.