more work on PGSQL 8.3 compatibility (refs #201)

functions.php

@@ -1108,8 +1108,8 @@
 
 				$result = db_query($link, "SELECT 
 						id,content_hash,no_orig_date,title,
-						substring(date_entered,1,19) as date_entered,
+						".SUBSTRING_FOR_DATE."(date_entered,1,19) as date_entered,
-						substring(updated,1,19) as updated,
+						".SUBSTRING_FOR_DATE."(updated,1,19) as updated,
 						num_comments
 					FROM 
 						ttrss_entries 

modules/pref-feed-browser.php

@@ -44,8 +44,8 @@
 				$result = db_query($link, "SELECT 
 						ttrss_entries.title,
 						content,link,
-						substring(date_entered,1,19) as date_entered,
+						".SUBSTRING_FOR_DATE."(date_entered,1,19) as date_entered,
-						substring(updated,1,19) as updated
+						".SUBSTRING_FOR_DATE."(updated,1,19) as updated
 					FROM ttrss_entries,ttrss_user_entries
 					WHERE	ttrss_entries.id = ref_id AND feed_id = '$id'
 					ORDER BY updated DESC LIMIT 5");

modules/pref-feeds.php

@@ -821,7 +821,7 @@
 				F1.id,
 				F1.title,
 				F1.feed_url,
-				substring(F1.last_updated,1,16) AS last_updated,
+				".SUBSTRING_FOR_DATE."(F1.last_updated,1,16) AS last_updated,
 				F1.parent_feed,
 				F1.update_interval,
 				F1.last_error,