Rename class attributes and parameters to be more Pythonic

[djordon]

There are a few attributes, such as: nAgents, nEdges, nEvents, nVertices, nBlocked, and nNodes, that are un-pythonic, and should probably be renamed to num_*. Keep the old names as properties but promote the new names in the documentation.

[djordon]

Also includes nArrivals, nDepartures, nSystem, and nServers in QueneServer class.

Every variable will be retained for now and not formally deprecated.