Docs on how to export images as png/svg

[ricklupton]

We need explicit examples of how to save Sankey diagrams as png/svg for further processing.

There is an example in the quickstart tutorial (cell 8) but it's not obvious.

@coenraadwestbroek does that help? use

weave(sdd, flows).to_widget().auto_save_png('filename.png')

or

weave(sdd, flows).to_widget().auto_save_svg('filename.svg')

The SVG you can open in Inkscape or another editor to tweak the text positions etc.

[coenraadwestbroek]

That works perfectly, thanks rick lupton!