artdaq

Right now, despite request source information being in the Request message, Request Receiver essentially ignores this information.

The destination rank is also in the RequestHeader struct, preventing a RoutingMaster from packing multiple requests on behalf of different destinations into a single datagram.

The rank field should be moved from RequestHeader to RequestPacket, and RequestReceiver's API should be updated to provide access to the timestamp, destination, and reception time (and/or all three at once) for a given Sequence ID, and to provide this information for all currently-active requests it knows about.