No need for this here, especially because this file is in the walkthrough
and will be found by web crawlers.

Reported-by: Julius Bachnick

Now, the majority the install can be done with one line, but the other
to each part of the install is still available.

Also fix a few bugs and add Wireshark coloring rules.

Still could be better though.... and we need more topology
examples.

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...

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

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.