introduce expand string modifiers, diff by Colin Didier
prepare code for hanling setuid/chroot in external table backends.
disabled for now since it requires changes in the bootstrapping
Prepare for setuid/chroot in external queue process.
Does not work for now. Need to tweak bootstrapping.
Merge branch 'master' into issue248-expand-modifiers
missing include
- do not allow the use of an unknown modifier
only remove the incoming dir if running in server mode
Document how the default server name is determined
Show one accept message per rcpt for the same message
Allow to restrict the address family used for smtp and mta in the
configuration file:

listen on <iface> [inet4|inet6] ...

limit mta [for domain my.domain] [inet4|inet6]
fix bug in envelope cache
Automatically detect if asr needs to be built along with smtpd
Merge branch 'master' into issue248-expand-modifiers
fix modifiers and document the feature
Do not schedule mta envelopes in batch.
Allow individual envelopes to be suspended in the scheduler.
Associated commands are:

smtpctl pause envelope <id>
smtpctl resume envelope <id>
Merge branch 'master' of ssh://ssh.poolp.org/git/opensmtpd
tls perfect forward secrecy with ecdhe

suggested by djm@ on hackers@, diff ok djm@
Merge branch 'master' of ssh://ssh.poolp.org/git/opensmtpd
adding the file is better ...