improved start page performance; top rating statistics was very slow

needs a new database field with manual init, see db-changes.txt !

and fixed another recommendation bug:
- recommendations will not get lost when a user edits one of multiple logs
  for the same cache

htdocs/doc/sql/db-changes.txt

@@ -15,3 +15,7 @@ date         commit ID    change
                             - add caches.okapi_syncbase, initialize it and add corresponding index
                             - add and initialize cache_logs(_archived).okapi_syncbase
                           See installation instructions at http://code.google.com/p/opencaching-api
+
+2012-08-24                added cache_rating.rating_date and index 'date'; must be initialized by:
+                            UPDATE cache_rating SET rating_date = (SELECT MIN(`date`) FROM cache_logs WHERE cache_logs.cache_id=cache_rating.cache_id AND cache_logs.user_id=cache_rating.user_id AND cache_logs.type IN (1,7))
+                          added trigger cacheRatingBeforeInsert

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

@@ -668,6 +668,13 @@
 						INSERT IGNORE INTO `removed_objects` (`localId`, `uuid`, `type`, `node`) VALUES (OLD.`id`, OLD.`uuid`, 1, OLD.`node`);
 					END;");
 
+	sql_dropTrigger('cacheRatingBeforeInsert');
+	sql("CREATE TRIGGER `cacheRatingBeforeInsert` BEFORE INSERT ON `cache_rating`
+				FOR EACH ROW
+					BEGIN
+						SET NEW.`rating_date` = NOW();
+					END;");
+
 	sql_dropTrigger('cacheRatingAfterInsert');
 	sql("CREATE TRIGGER `cacheRatingAfterInsert` AFTER INSERT ON `cache_rating` 
 				FOR EACH ROW