Add sorting icons to other columns in index table

templates/index.html

@@ -35,11 +35,11 @@
 			<table class="message message-list">
 				<tbody>
 					<tr>
-						<th class="hash">SHA1 hash</th>
+						<th class="hash">SHA1&nbsp;&nbsp;<a href="index_hash_desc_0.html"><img src="up.png"></a><a href="index_hash_asc_0.html"><img src="down.png"></a></th>
 						<th class="from">From&nbsp;&nbsp;<a href="index_from_desc_0.html"><img src="up.png"></a><a href="index_from_asc_0.html"><img src="down.png"></a></th>
-						<th class="to">To</th>
+						<th class="to">To&nbsp;&nbsp;<a href="index_to_desc_0.html"><img src="up.png"></a><a href="index_to_asc_0.html"><img src="down.png"></a></th>
-						<th class="subject">Subject</th>
+						<th class="subject">Subject&nbsp;&nbsp;<a href="index_subject_desc_0.html"><img src="up.png"></a><a href="index_subject_asc_0.html"><img src="down.png"></a></th>
-						<th class="date">Date</th>
+						<th class="date">Date&nbsp;&nbsp;<a href="index_date_desc_0.html"><img src="up.png"></a><a href="index_date_asc_0.html"><img src="down.png"></a></th>
 						<th class="attachments">Att.</th>
 					</tr>
 					%(items)s