QPID-5637: reset Selector singleton across fork.

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1596341 13f79535-47bb-0310-9956-ffa450edef68
QPID-5557: allow disambiguation of node type

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1571459 13f79535-47bb-0310-9956-ffa450edef68