Add support for generating man page from mn --help.

Makefile

@@ -1,7 +1,8 @@
 MININET = mininet/*.py
 TEST = mininet/test/*.py
 EXAMPLES = examples/*.py
-BIN = bin/mn
+MN = bin/mn
+BIN = $(MN)
 PYSRC = $(MININET) $(TEST) $(EXAMPLES) $(BIN)
 MNEXEC = mnexec
 P8IGN = E251,E201,E302,E202
@@ -34,6 +35,12 @@ develop: $(MNEXEC)
 	install $(MNEXEC) /usr/local/bin/
 	python setup.py develop
 
-doc:
+man: mn.1
+
+mn.1: $(MN)
+	help2man -N -n "create a Mininet network." --no-discard-stderr $(MN) \
+    > mn.1
+
+doc: man
 	doxygen doxygen.cfg
 

bin/mn

@@ -134,7 +134,11 @@ class MininetRunner( object ):
             else:
                 raise Exception( 'Custom file name not found' )
 
-        opts = OptionParser()
+        desc = ( "The %prog utility creates Mininet network from the\n"
+                 "command line. It can create parametrized topologies,\n"
+                 "invoke the Mininet CLI, and run tests." )
+
+        opts = OptionParser( description=desc )
         addDictOption( opts, SWITCHES, SWITCHDEF, 'switch' )
         addDictOption( opts, HOSTS, HOSTDEF, 'host' )
         addDictOption( opts, CONTROLLERS, CONTROLLERDEF, 'controller' )
@@ -175,6 +179,10 @@ class MininetRunner( object ):
         opts.add_option( '--pin', action='store_true',
                          default=False, help="pin hosts to CPU cores "
                          "(requires --host cfs or --host rt)" )
+        def fakeversion( *args ):
+            "Fake version for help2man"
+            print "mn (development version)"
+        opts.add_option( '--version', action='callback', callback=fakeversion )
 
         self.options, self.args = opts.parse_args()