"Etc/UTC" timezone

git-tfs-id: [http://falcon:8080/tfs/Projects]$/Phalanger/Main;C3916
sessions:
- session_regenerate_id(true) does not clear $_SESSION variable
- "files" session handler fix for data > 8kB
- API for session_name($newname)
- session id of empty session is not lost

git-tfs-id: [http://falcon:8080/tfs/Projects]$/Phalanger/Main;C3917