Bump heartbeat version to handle Class entry in session (v6).
Re-arrange session struct to remove padding.
Update cluster code to handle v6 packets. Drop compatability for pre-v5.
thanks. Changes:
- Handle session shutdown gracefully regarding leaving the bundle (bug that is
caused when a all session leaves a bundle then another join)
- IP assignment is done only for the first session in the bundle (save IP
waste for multiple MLPPP sessions)
- Route is being added only for the first session in the bundle (less routes
on l2tpns system)
- Fix route deletion problem for MLPPP sessions (bug that caused when a
session leaves a bundle)
- Uniformity of sequence number space satisfied (according to RFC1990)
- Fix reassembling fragmented packets and handling lost fragments (according
to RFC 1990)
- FragmentatConnection to l2tpns.cvs.sourceforge.net closed by remote host.n
across N session rather than two)
- Sequence numbers extraction mask has been corrected (bug in extracting
sequence numbers)
- some clustering support fixes
- Upload/Download statistics has been corrected
- add "kill_timedout_sessions" config option
