cmRtNetEndpointIsValid(),cmRtNetEndPointId(),cmRtNetEndPointLabel().
Added srcEndPtId to all 'sending' functions.
_cmRtNetRecv() now sets cmRtNetMsg_t.srcNodeIdx.
cmRtNet.h/c : The rtSubIdx of the owning cmRtSys sub-system is now set in
cmNetAlloc(). rtSubIdx is no longer required to locate a remote endpoint
because IP/"node label" is enough information to determine the rtSubIdx.
Several changes were made to simplify the interface to cmRtNet based on this
observation.