print -> info; end the horror of print vs. print()

Although we could use print() from __future__, this messes
up scripts which use examples as modules.

The simple, if not nicest for 2.7, solution is to use
info(), output() and other mininet.log functions. The disadvantage
is that we may have to adjust things if we change info() to
add automatic newlines, but we can burn that bridge in Mininet
3.x.

examples/multiping.py

@@ -12,7 +12,7 @@ of time.
 from mininet.net import Mininet
 from mininet.node import Node
 from mininet.topo import SingleSwitchTopo
-from mininet.log import setLogLevel
+from mininet.log import info, setLogLevel
 
 from select import poll, POLLIN
 from time import time
@@ -35,8 +35,8 @@ def startpings( host, targetips ):
             ' done; '
             'done &' )
 
-    print( '*** Host %s (%s) will be pinging ips: %s' %
-            ( host.name, host.IP(), targetips ) )
+    info( '*** Host %s (%s) will be pinging ips: %s\n' %
+          ( host.name, host.IP(), targetips ) )
 
     host.cmd( cmd )
 
@@ -70,7 +70,7 @@ def multiping( netsize, chunksize, seconds):
         readable = poller.poll(1000)
         for fd, _mask in readable:
             node = Node.outToNode[ fd ]
-            print( '%s:' % node.name, node.monitor().strip() )
+            info( '%s:' % node.name, node.monitor().strip(), '\n' )
 
     # Stop pings
     for host in hosts: