t/ cleanups

	modified:   t/ffi/context.t
	new file:   t/poex/zmq.t
	renamed:    t/poex/constants.t -> t/poex/zmq/constants.t
	renamed:    t/poex/socket_bare.t -> t/poex/zmq/socket.t
	renamed:    t/poex/types.t -> t/poex/zmq/types.t
kill stray empty file

	deleted:    lib/POEx/ZMQ/Subscriber.pm
fix ZMQ::Socket->send

	modified:   lib/POEx/ZMQ/Socket.pm
Types; ZMQSocketType should fail 'better'

	modified:   lib/POEx/ZMQ/Types.pm
POD