PR_erlang-p1-xmpp

Support building specs when using rebar3

Use include_lib() to include headers from dependency

This allows setting USE_REBAR3 variable to support building specs when library
has been compiled with rebar3. Default behaviour is unchanged.

Bad-protocol is not valid sasl error, it was only used pre-rfc protocol.

Add support for XEP-0215: External Service Discovery

Sync stop manually calls terminate callback, which skip parts of cleanup
that p1_server performs before it calls it, this results in messages
that p1_server queued in collect_messages never being seen by c2s process.

Async stop don't do that so let's try to remove all calls to sync version
with async ones, to help with handling this, i added stop_async, and marked
stop as deprecated.

The "urn:xmpp:carbons:rules:0" namespace was added to XEP-0280, version
0.13.0 (2019-04-24).

* processone/pr/46:
  Fix spelling of "inifinity" two times.