Apply MLPPP patch from Muhammad Tayseer Alquoatli, very belatedly, with

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

etc/startup-config.default

@@ -41,6 +41,9 @@ set radius_secret "secret"
 # Allow multiple logins for the same username
 #set allow_duplicate_users no
 
+# Kill timedout sessions ? (default yes)
+#set kill_timedout_sessions no
+
 # Allow multiple logins for specific username
 #set guest_account ""