irunner: doc update

add a sentence on purpose of irunner to manpage and update link
to origin

IPython/lib/irunner.py

@@ -16,7 +16,7 b' simply run the module as a script:'
 This is an extension of Ken Schutte <kschutte-AT-csail.mit.edu>'s script
 contributed on the ipython-user list:
 
-http://scipy.net/pipermail/ipython-user/2006-May/001705.html
+http://mail.scipy.org/pipermail/ipython-user/2006-May/003539.html
 
 
 NOTES:

docs/man/irunner.1

@@ -10,6 +10,8 b''
 .SH DESCRIPTION
 irunner is an interface to the various interactive runners
 available in IPython's \fBirunner\fP module. 
+It can used to run scripts as if they where typed up
+interactively.
 .PP
 The already implemented runners are listed below; adding
 one for a new program is a trivial task, see the source
@@ -42,7 +44,7 b' irunner.py \\-\\-ipython \\-\\- \\-\\-interact script.ipy'
 .SH AUTHOR
 \fBirunner\fP is an extension of Ken Schutte <kschutte-AT-csail.mit.edu>'s
 script contributed on the ipython-user list:
-http://scipy.net/pipermail/ipython-user/2006-May/001705.html
+http://mail.scipy.org/pipermail/ipython-user/2006-May/003539.html
 .PP
 This manual page was written by Bernd Zeimetz <[e-mail]>, for the Debian
 project (but may be used by others).  Modified by Fernando Perez