Pull requests from #129 to ##203 Includes the following changes - More strict HELO, EHLO, MAIL and RCPT command parsing - Code clean-ups, style fixes, etc - Fix EOF when parsing the envelope headers #142 - Fixes issue #148 - use the *validate* processor for validation - FreeBSD compatibility - SQL Statement configurable for different SQL databases, not just MySQL - add able to configure DB connection limits in sql backend - bug fix: server-log was incorrectly pointing to the main-log #180 - Support for TLS 1.3 - Issues #195 to #201 raised by @issuefiler, mostly fixing edge cases with handling IP addresse-literals and other inconsistencies related to rfc5321

Merge branch 'athoune-dep' 

- update readme - return error if can't bind