add a piechart of group memberships of a node to a network plot; taken mainly from latentnet equivalent
vblpcmdrawpie(center,radius,probs,n=50,colours=1:length(probs))
where to postion the piechart
radius of the piechart / node
probability vector of cluster memberships
order of polygon to approximate a circle
the colours used; default is from palette()
Michael Salter-Townshend
plot.vblpcm