Integrate possibility to save Graphs within GraphPlots

[oskarpfeffer]

I wondered why you didn't include the possibility to save graphs within GraphPlots and instead make people use Compose externally. I think it would be quite useful.

[hdavid16]

Saving to SVG would be easy, just need to export SVG from compose
Saving to PDF of PNG requires Cairo and Fontconfig as dependencies...

So it depends on if the developers want to add extra deps