Function as nodeRepulsion option

[mikpom]

I was wondering if I could use arbitrary function as layout option nodeRepulsion argument?
Cose layout in the core allows that but I am getting an error if when using the same function for cose-bilkent.

Thanks,
Mikhail

[maxkfranz]

This is a good idea, but I would argue that it's generally more useful to set functions for the edge options, like the edge length. Anyway, all element-related options should allow functions for per-element values -- like regular COSE -- not just node charge.

[DukeBaird]

A function for node repulsion or edge length would be quite helpful for me. I tried a quick modification but it seems to be more complicated that I had thought.

[bradh]

I just added a PR for edge length if you want to try it out - see #74

[ugurdogrusoz]

This is a duplicate of #1.