Clean up date and timezone handling.
We used to pass changelog dates around as a "unixtime timezone" string
containing a pair of encoded ints. Now, they get passed around as a
(unixtime, timezone) tuple of numbers, which makes much more sense.
#header#
<title>Mercurial repositories index</title>
</head>
<body>
<h2>Mercurial Repositories</h2>
<table>
<tr>
<td>Name</td>
<td>Description</td>
<td>Contact</td>
<td>Last change</td>
<td> </td>
<tr>
#entries%indexentry#
</table>
#footer#