mod_{dialback/s2s/tls}, util.s2smanager: refactor code... (Fixes #173)
- Add configurable exclusion lists for non-manifesto compliant
servers/services this should help with Google, Cisco etc.
- Also allow incoming pre-1.0 streams, as OpenFire as some other
old / obsolete servers will do DB on pre-1.0 streams while use
1.0 ones for everything else.