replace discussion links on pages with comments link

The thinking here is that having both a Discussion page and comments for
the same page is redundant, and certianly not what you want if you enable
comments for a page. At first I considered making configurable via pagespec
what pages got discussion links. But that would mean testing a new pagespec
for every page, and a redundant config setting to keep in sync. So intead,
take a lead from my previous change to make inlined pages have a comments
link, and change the discussion link at the top of regular pages to link to
their comments.

(Implementation is a bit optimised to avoid redundant pagespec checking.)

IkiWiki/Plugin/comments.pm

@@ -529,10 +529,11 @@ sub pagetemplate (@) {
 
 	my $page = $params{page};
 	my $template = $params{template};
+	my $shown = ($template->query(name => 'commentslink') ||
+	             $template->query(name => 'comments')) &&
+	            commentsshown($page);
 
 	if ($template->query(name => 'comments')) {
-		my $shown = commentsshown($page);
-
 		my $comments = undef;
 		if ($shown) {
 			$comments = IkiWiki::preprocess_inline(
@@ -563,7 +564,7 @@ sub pagetemplate (@) {
 		# the link. But, to update the number, blog pages
 		# would have to update whenever comments of any inlines
 		# page are added, which is not currently done.
-		if (commentsshown($page)) {
+		if ($shown) {
 			$template->param(commentslink =>
 				htmllink($page, $params{destpage}, $page,
 					linktext => gettext("Comments"),

templates/page.tmpl

@@ -49,9 +49,13 @@
 <TMPL_IF NAME="PREFSURL">
 <li><a href="<TMPL_VAR PREFSURL>">Preferences</a></li>
 </TMPL_IF>
+<TMPL_IF NAME="COMMENTSLINK">
+<li><TMPL_VAR COMMENTSLINK><br /></li>
+<TMPL_ELSE>
 <TMPL_IF NAME="DISCUSSIONLINK">
 <li><TMPL_VAR DISCUSSIONLINK><br /></li>
 </TMPL_IF>
+</TMPL_IF>
 </ul>
 </div>
 </TMPL_IF>