Add support for XEP-0198: Stream Management

- De-duplicate code by moving it into AbstractXMPPConnection
- Introduce TopLevelStreamElement as superclass for all XMPP stream elements.
- Add SynchronizationPoint, ParserUtils
- Add ParserUtils

Fixes SMACK-333 and SMACK-521

documentation/extensions/streammanagement.md

@@ -0,0 +1,37 @@
+Stream Management
+=================
+
+XMPPTCPConnection comes with support for Stream Management (SM).
+
+**XEP related:** [XEP-0198](http://xmpp.org/extensions/xep-0198.html)
+
+Known interoperability issues
+-----------------------------
+
+- SM resumption failes on prosody when compression in sync flush mode is used with prosody. See [Prosody issue #433](https://code.google.com/p/lxmppd/issues/detail?id=433).
+
+Enabling stream management
+------------------------
+
+TODO
+
+Getting notifications about acknowledges stanzas
+------------------------------------------------
+
+TODO
+
+Requisting stanza acknowledgements from the server
+--------------------------------------------------
+
+### By using predicates
+
+TODO
+
+### Manually
+
+TODO
+
+Enable stream resumption
+------------------------
+
+TODO