This commit adds
- SmackReactor / NIO
- a framework for finite state machine connections
- support for Java 8
- pretty printed XML debug output
It also
- reworks the integration test framework
- raises the minimum Android API level to 19
- introduces XmppNioTcpConnection
Furthermore fixes SMACK-801 (at least partly). Java 8 language
features are available, but not all runtime library methods. For that
we would need to raise the Android API level to 24 or higher.
Smack's previous entity caps implementation assumed that an entity lost
its entity caps feature as soon as a presence without caps from that
entity was received. But according to XEP-0115 § 8.4, this is a
perfectly normal optimization technique. We now reset the caps state
after an available presence becomes unavailable.
Also introduce PresenceEventListener, which is required for this
feature.
Also make Roster.preApprove() take a BareJid as argument.
Fixes SMACK-723.