First attempt at an implementation of a non-blocking shared port client.
Fix handling of NULL char *; fix non-blocking logic. #4094
Mark socket as non-blocking when a connection attempt is made. #4094

This causes clients to be rejected as soon as the daemon's backlog
is hit.  This is equivalent behavior to the case where the daemon
is listening on the network and the TCP socket backlogs.
ifdef out portions which will not compile under Windows. #4094
Add support for callbacks in the Schedd.query method.
Allow DC sockets to be registered for write.
Allow CEDAR to indicate when there is a backlog for sending packets to the network.  Use this to implement a putClassAd variant which can detect backlog.
WARNING.  This breaks the condor_q wire protocol to allow streaming of ClassAds.
Debug non-blocking mode of ReliSock. #0

Start to make condor_q responses non-blocking.
Initial implementation of server-side for a non-blocking condor_q protocol.