As not including "role='none'" when kicking a user will result in an
XMPPErrorException. Also there appears to be nothing in XEP-45 which
says "if role is not set, then it defaults to 'none'".
- 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
Removes a ton of duplicate code, mostly related to MUCItem being
duplicated in MUCOwner and MUCAdmin, but also some other duplicate code.
Make MUC code use XmlStringBuilder.
Add ELEMENT and NAMESPACE constants to the appropriate places. Also add
"static <MUCPacketExtension> getFrom(Packet)" methods.
Make some MUC classes implement Element.