[PATCH] session module

Hi all, If you have comments, please feedback before I apply this patch. Attached patch fixes many problems in session module. It also breaks some of script which barely worked before. This patch fixes: - Crashes are caused by invlaid save_path, invalid session id name, return value from user defined session function. There may be other crashes observed that I don't know. - Broken mm save handler. - Sticky session module name - Change error level for failure to open session. (E_ERROR -> E_WARNING) - Dead lock with files handler - Prevent calling session_name() and session_set_cookie_parameter() once session is started. It doesn't work after session is started, anyways. - Prevent to set module name after session is started. (This causes dead lock with files hadler. It may do something bad for other save handlers also. It should be prevented, IMO.) The last fix will break some scripts. -- Yasuo Ohgaki