QPID-4822: Allow Variant::parse() to produce VAR_UINT64 types.
- Extend qpid::messaging::Variant string parser to output unsigned 64 bit
  type where relevant (positive integer larger than signed 64 bits)
- Added some unit tests for the qpid::messageing::Variant string parser

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1480376 13f79535-47bb-0310-9956-ffa450edef68
QPID-4821: speed up selector identifier lookups

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1480377 13f79535-47bb-0310-9956-ffa450edef68