[Critical] Typo in variable name due to which edge weights don't work

[virresh]

Line https://github.com/fkling/JSNetworkX/blob/master/src/drawing/svg.js#L266

the variable is misspelled as weigths whereas the correct code should contain weights in the switch case

I would be happy to send a PR if this project is still maintained ?

[virresh]

Possibly also the cause for #78

[virresh]

I've done this for the temporary fix: https://github.com/virresh/JSNetworkX/releases/tag/v0.3.4.1

There's a sample fiddle link for a working example.