add net building by rejection.
factor out greedy routing
route to 10 targets per network.
factor out pathfolding.
allow for arbitrary rejection functions.
separated plotting from optimization to be able to harness the power of pypy.
polish
adjust params.
adjust params.
10000 nodes, backoff 0.3
add rejectnever function for pathfolding.
reject: do not take the first peer at random: if there are no peers, reject based on 0.001/dist: start out with short connections.

--HG--
extra : amend_source : a9fc290481f29f85d809a371dba3fe8026c94f9d
plot: only by-distance and reject in the second plot..
pathfold all networks.
merge