Import lua filters

 WARNING It's only compatible with lua52 (at least only tested with 5.2)

 TODO:

 - Implement commit/rollback
 - Implement disconnect
 - Find how to check for lua-5.2 in configure
Test if lua function exists before registering them
do no build lua filter yet

Conflicts:
	mk/filters/Makefile.am
disable the imsg buffers profiling code unless requested, this will prevent all
processes waking up every second
ASR field renames
do not add a user-agent
a queue user is mandatory, do not attempt _smtpd and fallback to _smtpq
more informative log message on unknown SNI.
remove old instructions about sendmail
do not call purge_task every 10 secs, it is only needed once at startup and
will cause the parent process to wake up unnecessarily at runtime
Merge branch 'master' into portable

Conflicts:
	smtpd/smtpd.8
Merge branch 'portable' of https://github.com/poolpOrg/OpenSMTPD into portable