Also remove all non-object-oriented legacy Mininet code and update
tests.
User-space compatibility is untested, but most of the code for it is
still in.
Nodes include Switch, Host, and Controller; move these to a separate
file.
This file still could use some attention to hide private functions.
Node seems like a primary class to extend, for adding stuff like Open
vSwitch, so it could benefit from a simpler interface.
Having a file with the same name as its package creates hard-to-diagnose
import error, so rename mininet.py to net.py. This commit moves utility
functions, generally those dealing with network namespaces and interface
management, into their own file.
Also fix a few minor formatting bugs and clean up logging code (which
had issues when multiple files would import mininet.logging_mod).
Brandon Heller