There is some issue on binding raw ICMPv6 socket immediately after assigning address on 3.14 (and probably later) kernel.
This causes ipv6_nd to fail to start.
This patch makes ipv6_nd to try to bind later if bind fails.

Previous version used linear list of vlan monitor enabled interfaces,
this caused huge overhead in packet receive path because for each
received packet it performed search on linear list to check if vlan monitor
is enabled on input device.
Current version binds internal structure to net_device->ml_priv so search is not performed more.

With unblocked signals log thread may catch SIGCHLD which causes zombie process.

If specified then accel-ppp will send tunnel type as string (pppoe,pptp,l2tp,ipoe).

Passed strings was not nullterminated

Before this time accel-ppp always worked in "ip unnumbered" mode.
This option may turn this mode off (default is on)

After introduction offer-delay accel-ppp stopped to answer NAK for REQUESTs if requested session is not existing
to give chance other servers to reply. But this causes that some broken clients enter to infinite REQUEST loop.
This patch corrects this issue, so if offer-delay is not configured (means that this is only server in the net) or
after receiving few REQUESTs accel-ppp send NAK for non-existing sessions.

This reverts commit c317ff51.

First try to rename interface immediately and if it fails then do second try later just before bring interface up.
In case single-session=replace first try to rename interface may fail because first session may be active

Use separated thread to write messages to file instead of async io.
On mips platform async io does not work properly by some reason and may stuck logging

Check if there is space in previous chunk and append log data there.
This reduces memory usage and message fragmentation

Wait for previous session completely terminated before continuing authorization new session.

New options are applied to server option as server=...[,weight=x][,backup]
Weight is used for multi-server configurations (larger weight takes more users).
Backup is used to mark backup server f.e. server which will be used only if all other servers are failed.