Fix svg_dual_links demo + expose renderer.isPaused variable

Hello @anvaka,

I have created a PR about fixing the dual links demo for tutorial_svg, using the multigraph option. Just mention it here as an issue for people that would like to create a multigraph. I think that it's not documented somewhere.

Also, I have included another commit to expose the _isPaused_ variable to the renderer object.

Thanks!

Start with the tutorial_svg dual-links demo and the renderer API entry point; the issue mentions the multigraph option and exposing renderer.isPaused, but names no files or tests. Confirm the demo works with multigraph links and that the pause state is externally visible, then document how to create a multigraph.

Written by the indexing model from the issue text.