Restored scratchnet and scratchnetuser demos.
Also changed the str format for nodes to use str() ratherthan repr() so we don't end up with extraneous quotes.
Moved link creation into Node.addIntf() and fixed util:CreateLink().
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.
Use setuptools to install python files
Now, to reference mininet files, use 'import mininet.mininet'.
PYTHONPATH mods are no longer required for installation.
Minor tweaks and corrections.Added commentary on control network to mininet.py.Hopefully fixed linearbandwidth.py for real.
Added "from scratch" examples, to show how to create a network usinglow-level primitives.
The "nox.py" example attempts to use nox as a controller rather thancontroller(8).
More edits for INSTALL and README, and refinements for sshd and xtermexamples.