Merge branch 'af_unburn_fetch_only_headers' into 'master'

af_unburn: Fetch only the headers in order to get the real article URL.

As discussed in the forum https://tt-rss.org/forum/viewtopic.php?f=8&t=3631 , this change makes af_unburn download only the headers in order to find the real URL, saving bandwidth.

See merge request !21

plugins/af_unburn/init.php

@@ -30,6 +30,7 @@ class Af_Unburn extends Plugin {
 				curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
 				curl_setopt($ch, CURLOPT_HEADER, true);
 				curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
+				curl_setopt($ch, CURLOPT_NOBODY, true);
 				curl_setopt($ch, CURLOPT_USERAGENT, SELF_USER_AGENT);
 
 				if (defined('_CURL_HTTP_PROXY')) {