put the necessary files for building debian package
add a target `deb` of Makefile to build debian package
add manpage

The file is generated by command `ronn`.
avoid deadlocks when the LOG_LEVEL is set to DEBUG

`fprintf` and `syslog` are thread-safe but not reentrant.
If a signal happen during those functions and the handler calling them
again, the deadlock is form.  Therefore, we need to block signals until
we leave they realm.
update changelog
Quickly update documentation for new permissions drop, log ,ulog

Signed-off-by: Etienne CHAMPETIER <etienne.champetier@free.fr>