improved single-session=replace handling

Wait for previous session completely terminated before continuing authorization new session.
log: append data to previous chunk

Check if there is space in previous chunk and append log data there.
This reduces memory usage and message fragmentation
log_file: rewrited file write procedure

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
Merge branch 'master' of ssh://git.code.sf.net/p/accel-ppp/code
2-way interface renaming

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
ipoe: use ifindex as connlimit key for non-shared interfaces
triton: fix possible race
ipoe: add messages to know parent interface when creating vlan or virtual interface
triton: fix possible race
cmake: restore Debian6 specific install rules
Revert "cmake: restore Debian6 specific install rules"

This reverts commit c317ff519717c5c9f0513b85bb7d10ba084c74e9.
cmake: restore Debian6 specific install rules
log_file: restore write message timestamps
ipoe: set initial session interface name to parent interface name (for logging purpose)
ipoe: send NAK after number of unreplied REQUESTs

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.
ipoe: introduced "ip-unnumbered" option

Before this time accel-ppp always worked in "ip unnumbered" mode.
This option may turn this mode off (default is on)
More merges
...
Merge branch 'master' of git://git.code.sf.net/p/accel-ppp/code