To provide donut shaped vertices

[ntamas]

From @cndesantana on July 15, 2017 3:38

Hi,

It would be nice if we could plot donut shaped vertices (donut/torus/ring/...). I know it is possible to plot a donut-vertex by plotting a pie-vertex with a smaller circle-vertex inside. But I wonder it would be much nicer if the donut-shaped was defined in Igraph. We could get inspiration from Plotly: https://plot.ly/r/pie-charts/undefined

Thanks

Copied from original issue: igraph/igraph#1014

[ntamas]

Vertex drawing is specific to the R interface so I'm moving this issue there.