Clear write buf when a close has been called

	modified:   lib/POEx/ZMQ3/Sockets.pm
Safer tests.

	modified:   t/01_component/pub_sub.t
	modified:   t/01_component/pub_sub_multi.t
	modified:   t/01_component/rep_req.t
	modified:   t/02_subclass/publisher_subscriber.t
	modified:   t/02_subclass/requestor_replier.t
POD / cleanups

	modified:   lib/POEx/ZMQ3.pm
	modified:   lib/POEx/ZMQ3/Context.pm
	modified:   t/01_component/pub_sub.t
	modified:   t/01_component/pub_sub_multi.t
	modified:   t/02_subclass/publisher_subscriber.t