added support for commiting sessions(remove file lock for php sessions)

phpgwapi/inc/class.sessions.inc.php

@@ -212,6 +212,15 @@
 			}
 		}
 
+		/**
+		* commit the sessiondata to storage (needs to be reimplemented for the subclasses)
+		*
+		* @return bool
+		*/
+		function commit_session() {
+			return true;
+		}
+
 		function split_login_domain($both,&$login,&$domain)
 		{
 			$parts = explode('@',$both);

phpgwapi/inc/class.sessions_php4.inc.php

@@ -43,6 +43,16 @@
 			session_name('sessionid');
 		}
 
+		/**
+		* commit the sessiondata to the filesystem
+		*
+		* @return bool
+		*/
+		function commit_session() {
+			session_write_close();
+			return true;
+		}
+
 		function read_session()
 		{
 			if (!$this->sessionid)