fixed another trigger recursion when updating a cache record

function touchCache() in lib/clicompatbase.inc.php updated e.g. cache_desc.last_modified
in the same statement with an access to caches table. As the cacheDescAfterUpdate trigger
updates caches.listing_last_modified, the read & write access to caches table collided.

function touchCache() is obsolete, as touching on status change is done by triggers
for all depending tables (via SQL function sp_touch_cache).

htdocs/doc/sql/stored-proc/maintain.php

@@ -192,6 +192,12 @@
 					 UPDATE `caches` SET `last_modified`=NOW() WHERE `cache_id`=nCacheId;
 				 END IF;
 
+				 /* This is a hack for the XML interface which delivers cache-related records
+				  * like descriptions and pictures only depending on their last_modified date.
+				  * Data may not have been deliverd or stored somewhere depending on the cache 
+				  * status, so when status changes, all has to be sent (again) via XML.
+				  */
+
 				 UPDATE `cache_desc` SET `last_modified`=NOW() WHERE `cache_id`=nCacheId;
 				 UPDATE `cache_logs` SET `last_modified`=NOW() WHERE `cache_id`=nCacheId;
 				 UPDATE `coordinates` SET `last_modified`=NOW() WHERE `cache_id`=nCacheId AND `type`=1;