Instead of breaking in case the SSLEngine signals NEED_WRAP, which
leads to an endless loop while holding the
channelSelectedCallbackLock, we have to return, so that the
asynchronously invoked callback can aquire it, and do its work.
This continues the design started with e98d42790 ("SmackReactor/NIO,
Java8/Android19, Pretty print XML, FSM connections"), where the
exceptions that caused an operation to fail, are not recorded within
SynchronizationPoint but within the connection instance itself.
This moves the logic in AbstractXMPPConnection.getSmackTlsContext()
into the ConnectionConfiguration constructor.
Also introduce SslContextFactory and use it in
ConnectionConfiguration.
This is a complete redesign of what was previously
XmppNioTcpConnection. The new architecture allows to extend an XMPP
client to server (c2s) connection with new transport bindings and
other extensions.