[igraph] weighted centralities

[hamaina rachid]

Thank you Gabor. This is a part of my calculation. this example is from a pajek 
file, but the same happen with a "ncol" format.

> G<-read.graph("graphtest.net", format="pajek")
> G
Vertices: 7 
Edges: 6 
Directed: FALSE 
Edges:      
[0] 0 -- 1
[1] 0 -- 2
[2] 0 -- 3
[3] 4 -- 5
[4] 4 -- 6
[5] 0 -- 4
> E(G)$weight
[1] 10 15 95 32  5 25
> betweenness(G)
[1] 12  0  0  0  9  0  0
> betweenness(G, weights=NA)
[1] 12  0  0  0  9  0  0