Merge 0.12->trunk

mod_smacks: Fix to use current method of counting acked stanzas Fixes #1757 These places seem to have been left since e62025f949f9 The logic around expected_h in should_ack() misbehaved, always comparing with 0 + unacked instead of acked + unacked.

Merge 0.12->trunk

util.prosodyctl.check: Remove now redundant unbound config tweak This is now done in net.unbound itself Turning it back on in the config may still cause the problem of entries there masking the DNS values.

mod_smacks: Use session logging for remaining log messages For consistency and easier correlation of session events.

mod_smacks: Factor out some convenience functions Those lines are long and the risk of mistakes if another one needs to be added seems high, but lower when factored out like this.

util.stanza: Document top level attributes in Teal definition Tells you if you make a typo like "gropchat" or so

util.stanza: Document error conditions in Teal definition Gets you nice error messages if you make a typo in with error_reply()

net.server_epoll: Add option to defer accept() until data available This is a Linux(?) socket option that delays the accept signal until there is data available to read. E.g. with HTTP this might mean that a whole request can be handled without going back trough another turn of the main loop, and an initial client <stream> can be responded to. This may have effects on latency and resource use, as the server does not need to allocate resources until really needed.

net.server_epoll: Wrap LuaSocket object earlier to reuse option setting method Since it provides some protection and error handling in the form of logging.