fixed warnings

--HG--
extra : source : 69ecb1220185099f1ad165c137c5fcb6d0c79d04
extra : amend_source : 23600714597a348bb967f62489c6b94cab100993
use in-process server (Lwt_comm) over 'STOMP.stomp_frame' messages, to be able to embed ocamlmq in applications

--HG--
extra : rebase_source : 6a49104510728211ac95134b7714d584e10755f7
extra : amend_source : 729585842c101e79b6b660cdbb430945938444e3