s/http:\/\/openflow.org\/mininet/http:\/\/mininet.org/g

File and command names in typewriter text.

This isn't the final README text, of course, but it should
show up formatted now on github.

Added alpha releas comments, inc. do not distribute yet.

Added install notes for install.sh.

Added retry() function for createLink to see if it helps (probably won't.)
Random edits to docs.

Added scratchnetuser.

Fixed xterm.py (and cleanup) to clean up screen sessions.
Cleaned up sshd.py (though interface is still in flux.)
Added 1024-node network example (treenet1024.py).
Added example showing multiple tests on a single network (multitest.py).
Renamed examples to make them easier to type!

Other minor cleanup.