Removed "e" from Network type.
This wasn't actually used by anything, and is all information already contained in Network.g.
In case it ever is needed by someone, I added a function "getEdges(network)" that [inefficiently] regenerates the vector of edges, indexed by their edge indices.
This function was left internal, but was added to the routes.jl test.
Issue #42.

Signed-off-by: Ted Steiner <tsteiner2@gmail.com>