store: change `_walk` return to `(filename, (type, size))`
If we are to group file per revlog, having the filename as the "main key" will be useful. This change will make the following changes clearer.
{motd}
<div class="logo">
<a href="{logourl}">
<img src="{staticurl|urlescape}{logoimg}" width=75 height=90 border=0 alt="mercurial"></a>
</div>
</body>
</html>