Spectral radius

[tpoisot]

Add the spectral radius function - this is defined for any unipartite network, so bipartite networks simply need to be converted.

[tpoisot]

pinging @taddallas (just FYI)

[tpoisot]

Wait, @taddallas, this needs your input. Spectral radius depends heavily on the size of the matrix. So it seems to me that we should have some process to make it more standard. The two I can think of are either dividing by the sum of the absolute values of the real part of the eigenvalues, or to divide by the norm of the adjacency matrix, since it should be an upper bound for the spectral radius in most cases.

[tpoisot]

I'll go ahead and use the norm at the moment.

[tpoisot]

Let's close this one and have the discussion in the PR instead.