Prettify notebook plots

Check figure.max_open_warning for environmental barcode plots
Try to reproduce error in environmental barcode plots when ticking "Collapse" in certain settings
Heatmap: Do not allow 1e+02 numbers
Remove (fig, ax) prints below plots in notebooks (left-over TODO from https://github.com/dominiquesydow/dynophores/pull/33)
- https://github.com/jupyter-widgets/ipywidgets/pull/712
- Example: In notebook, between widget and plot:
```
(<Figure size 576x396 with 2 Axes>,
<AxesSubplot:xlabel='Superfeature IDs', ylabel='Environmental partner IDs'>)
```

wolberlab / dynophores