add workaround for psql 8.3 stricter typechecking on SUBSTRING() (refs #201)

modules/pref-feed-browser.php

@@ -16,7 +16,7 @@
 
 			$result = db_query($link, "SELECT 
 					feed_url,site_url,
-					SUBSTRING(last_updated,1,19) AS last_updated 
+					".SUBSTRING_FOR_DATE."(last_updated,1,19) AS last_updated 
 				FROM ttrss_feeds WHERE id = '$id' AND
 					auth_login = '' AND auth_pass = '' AND private IS NOT true");
 

modules/pref-feeds.php

@@ -804,7 +804,7 @@
 		if ($_GET["slat"] == "true") {
 			$show_last_article_info = true;
 			$show_last_article_checked = "checked";
-			$show_last_article_qpart = ", (SELECT SUBSTRING(MAX(updated),1,16) FROM ttrss_user_entries,
+			$show_last_article_qpart = ", (SELECT ".SUBSTRING_FOR_DATE."(MAX(updated),1,16) FROM ttrss_user_entries,
 				ttrss_entries WHERE ref_id = ttrss_entries.id
 				AND feed_id = F1.id) AS last_article";
 		} else if ($feeds_sort == "last_article") {

modules/pref-users.php

@@ -197,7 +197,7 @@
 
 		$result = db_query($link, "SELECT 
 				id,login,access_level,email,
-				SUBSTRING(last_login,1,16) as last_login
+				".SUBSTRING_FOR_DATE."(last_login,1,16) as last_login
 			FROM 
 				ttrss_users
 			ORDER BY $sort");