Feature: support any tag separator

So it allows to have multiple words tags.

Breaking change: commas ',' are no longer a default separator.

Fixes #594

application/render/PageBuilder.php

@@ -161,6 +161,7 @@ class PageBuilder
         $this->tpl->assign('formatter', $this->conf->get('formatter', 'default'));
 
         $this->tpl->assign('links_per_page', $this->session['LINKS_PER_PAGE'] ?? 20);
+        $this->tpl->assign('tags_separator', $this->conf->get('general.tags_separator', ' '));
 
         // To be removed with a proper theme configuration.
         $this->tpl->assign('conf', $this->conf);