Simplifies installation step

Defining custom topologies, switch types, controllers, and hosts is now
much easier.  Plus, all Ripcord-specific stuff has been moved out.

Shell now works (although we should use quietRun instead to avoid
file descriptor problem!)

exit/quit/EOF now all exit.

Renamed pingall and pingpair to make them easier to type - I think
commands should not require use of the shift key in general, although
ping-all and ping-pair might be OK.

Convert CLI to use Python Cmd object, which provides line editing.

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

does most of the work.)

topo.py is still in pep8, however

We may wish to re-enable this later.

Updated other files accordingly.

It's possible that mn_clean is a bit easier to read; mnclean may be easier
to type, however.

Added variables to Makefile so that source files are listed in a single
location.

The packages argument was incorrectly specified, leading to an install
process that would appear to have succeeded, but would not actually copy
code.

The error likely occurred due to copying setup.py from another project
where the source files were located in a different position relative to
setup.py.

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.

Possibly useful for adding custom port mappings.

Now you can run a controller on a remote PC that is
not on the same pc as Mininet.

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.

If ripcord.dctopo imports properly, then include its topologies in the
list of available ones.  Also replace topo.py with new generic
topologies and update paths.