further Context cleanup wrt _destroy going away

	modified:   lib/POEx/ZMQ/FFI/Context.pm
test outline

	new file:   t/ffi/socket.t
	new file:   t/poex/constants.t
	new file:   t/poex/socket_bare.t
	new file:   t/poex/types.t
FFI; add ->warn_if_error

	modified:   lib/POEx/ZMQ/FFI/Role/ErrorChecking.pm
FFI::Socket; call a zmq_close from DEMOLISH

	modified:   lib/POEx/ZMQ/FFI/Socket.pm
Fix FFI::Socket->send_multipart, BUILD

Initial ROUTER<->REQ test for same

	modified:   lib/POEx/ZMQ/FFI/Socket.pm
	modified:   t/ffi/socket.t