drop SIMPLE_UPDATE_MODE, limit housekeeping and updates to background processes

classes/Config.php

@@ -53,13 +53,6 @@ class Config {
 	 * your tt-rss directory protected by other means (e.g. http auth). */
 	const SINGLE_USER_MODE = "SINGLE_USER_MODE";
 
-	/** enables fallback update mode where tt-rss tries to update feeds in
-	 * background while tt-rss is open in your browser.
-	 * if you don't have a lot of feeds and don't want to or can't run
-	 * background processes while not running tt-rss, this method is generally
-	 * viable to keep your feeds up to date. */
-	const SIMPLE_UPDATE_MODE = "SIMPLE_UPDATE_MODE";
-
 	/** use this PHP CLI executable to start various tasks */
 	const PHP_EXECUTABLE = "PHP_EXECUTABLE";
 
@@ -205,7 +198,6 @@ class Config {
 		Config::DB_PORT => [ "5432",										Config::T_STRING ],
 		Config::SELF_URL_PATH => [ "https://example.com/tt-rss", Config::T_STRING ],
 		Config::SINGLE_USER_MODE => [ "",								Config::T_BOOL ],
-		Config::SIMPLE_UPDATE_MODE => [ "",								Config::T_BOOL ],
 		Config::PHP_EXECUTABLE => [ "/usr/bin/php",					Config::T_STRING ],
 		Config::LOCK_DIRECTORY => [ "lock",								Config::T_STRING ],
 		Config::CACHE_DIR => [ "cache",									Config::T_STRING ],