extdiff: add --change option to display single changeset diff
This is the counterpart for extdiff of
9c6ae2e09e11.
#header#
<title>Mercurial repositories index</title>
</head>
<body>
<div class="page_header">
<a href="http://www.selenic.com/mercurial/" title="Mercurial" style="float: right;">Mercurial</a>
Repositories list
</div>
<table cellspacing="0">
<tr>
<td><a href="?sort=#sort_name#">Name</a></td>
<td><a href="?sort=#sort_description#">Description</a></td>
<td><a href="?sort=#sort_contact#">Contact</a></td>
<td><a href="?sort=#sort_lastchange#">Last change</a></td>
<td> </td>
<td> </td>
</tr>
#entries%indexentry#
</table>
<div class="page_footer">
#motd#
</div>
</body>
</html>