Make cleanup a param of mn, not a separate script

Also switch from print to info statements, to enable a non-verbose
clean.  Instead of 'mnclean', now run 'mn -c'.

mininet/clean.py

@@ -0,0 +1,55 @@
+#!/usr/bin/env python
+
+"""
+Mininet Cleanup
+author: Bob Lantz (rlantz@cs.stanford.edu)
+
+Unfortunately, Mininet and OpenFlow (and the Linux kernel)
+don't always clean up properly after themselves. Until they do
+(or until cleanup functionality is integrated into the Python
+code), this script may be used to get rid of unwanted garbage.
+It may also get rid of 'false positives', but hopefully
+nothing irreplaceable!
+"""
+
+from subprocess import Popen, PIPE
+
+from mininet.log import info
+from mininet.xterm import cleanUpScreens
+
+def sh( cmd ):
+    "Print a command and send it to the shell"
+    info( cmd + '\n' )
+    return Popen( [ '/bin/sh', '-c', cmd ], stdout=PIPE ).communicate()[ 0 ]
+
+def cleanup():
+    """Clean up junk which might be left over from old runs;
+       do fast stuff before slow dp and link removal!"""
+    info("*** Removing excess controllers/ofprotocols/ofdatapaths/pings/noxes"
+         "\n")
+    zombies = 'controller ofprotocol ofdatapath ping nox_core lt-nox_core '
+    zombies += 'udpbwtest'
+    # Note: real zombie processes can't actually be killed, since they
+    # are already (un)dead. Then again,
+    # you can't connect to them either, so they're mostly harmless.
+    sh( 'killall -9 ' + zombies + ' 2> /dev/null' )
+
+    info("*** Removing junk from /tmp\n")
+    sh( 'rm -f /tmp/vconn* /tmp/vlogs* /tmp/*.out /tmp/*.log' )
+
+    info("*** Removing old screen sessions")
+    cleanUpScreens()
+
+    info("*** Removing excess kernel datapaths\n")
+    dps = sh( "ps ax | egrep -o 'dp[0-9]+' | sed 's/dp/nl:/'" ).split( '\n' )
+    for dp in dps:
+        if dp != '':
+            sh( 'dpctl deldp ' + dp )
+
+    info("*** Removing all links of the pattern foo-ethX\n")
+    links = sh( "ip link show | egrep -o '(\w+-eth\w+)'" ).split( '\n' )
+    for link in links:
+        if link != '':
+            sh( "ip link del " + link )
+
+    info("*** Cleanup complete.\n")