added INIT events for endpoints

commented out extraneous printfs
added new/incref/decref variants that take backpointers for logging; also fixed pn_inspect for pn_hash_t
fixed memory leak by making the transport clean up references held by the channel and handle maps; made use of the backpointer versions of new, incref, and decref to track down issue
implemented final events for proton-j; added tests for final events