Session class rewrite

create new session on class call, there is no need to delay that at all

new option to auto write close a session

session_id and session_name are stored as class vars

deprecate the __set/__get part because we do not want to set via ->session_var_name
but use the set()/get() methods.
They have been renamed from setS/getS... to set/get alone

www/lib/CoreLibs/Admin/Backend.php

@@ -403,7 +403,7 @@ class Backend
 				$_SERVER['HTTP_ACCEPT'] ?? '',
 				$_SERVER['HTTP_ACCEPT_CHARSET'] ?? '',
 				$_SERVER['HTTP_ACCEPT_ENCODING'] ?? '',
-				$this->session->getSessionId() !== false ?
+				$this->session->getSessionId() !== '' ?
 					$this->session->getSessionId() : null,
 				// row 4
 				$this->action ?? '',