We need to figure out how to specify the IP addresses for the
routed control network. For now I'm going back to 192.168.12x.y

Also changed controller params to use IP strings rather than
numbers. However, we still need to clarify what ControllerParams
is actually for.

Also print warning if user chooses a loglevel that will hide CLI output.

Also tweaked cmd/cmdPrint to make them more beautiful and functional,
and a few other minor changes, such as using a new idiom for verbose.

These changes support reinstating the examples.

All commands should work now.

There is probably a better way of doing this, but currently
parseCustomFile can modify globals (e.g. TOPOS) as well as
instance variables (self.validate) and classes (e.g. MyTopo),
which are also in the global name space.

Inconveniently enough, lambdas don't seem to be full closures
in Python; if they were, this trickiness would be unnecessary.

Even so, using execfile() seems like it might be a bit dubious...

This increases flexibility by allowing a topology to be manually created
in Python, or specified using another format, without having to create
a Topo object first.

However, Topos are useful, and are still the default topology object!

with the exception of topo.py, which I haven't touched.

- some namespace conflicts due to unpep8
- fixed infinite recursion caused by removing redundant makeIntfPair

'unpep8' script, which does most of the work.

- topo.py is still in pep8
- not all examples work, but this is due to other issues

Updated other files accordingly.

This required a change to logging, which now uses a singleton pattern.

For all future checkins, 'make codecheck' should pass.

Switches and controller in root namespace only, for now.

Sort interface names before passing to dpctl for kernel switch, so that
links for multipath topologies can be added in any order.

Also use indexing for DPIDs to avoid zeroed MAC

Auto MAC setup sets each host MAC equal to its DPID, which simplifies
debugging.

Auto ARP setup removes the need for broadcast support for ARP, which
enables a smaller NOX controller.

Also simplify test running.

Also remove usused imports and outdated doc text.

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.