qpid::client::Message::send multiple memory leaks

There may be multiple leaks of the outgoing message structure and associated fields when using the qpid::client::amqp0_10::SenderImpl::send function to publish messages under certain setups. I will concede that there may be options that are beyond my ken to ameliorate the leak of messages structures, especially since there is an indication that under prolonged runs (a demonized version of an application like spout) that the statistics for quidd indicate increased acquires with zero releases.

The basic notion is illustrated with the test application spout (and drain).  Consider a long running daemon reducing the overhead of open/send/close by keeping the message connection open for long periods of time.  Then the logic would be: start application/open connection.  In a loop send data (and never reach a close).  Thus the drain application illustrates the behavior and demonstrates the leak using valgrind by sending the data followed by an exit(0).  

Note also the lack of 'releases' associated with the 'acquires' in the stats output.

Capturing the leaks using the test applications spout/drain required adding an 'exit()' prior to the close, as during normal operations of a daemon, the connection remains open for a sustained period of time, thus the leak of structures within the c++ client library are found as structures still tracked by the library and cleaned up on 'connection.close()', but they should be cleaned up as a result of the completion of the send/receive ack or the termination of the life of the message based on the TTL of the message, which ever comes first.  I have witnessed growth of the leaked structures into the millions of messages lasting more than 24hours with short (300sec) TTL of the messages based on scenarios attached using spout/drain as test vehicle.

The attached spout.log uses a short 10message test and the spout.log contains 5 sets of different structures leaked (found with the 'bytes in 10 blocks are still reachable' lines, that are in line with much more sustained leaks when running the application for multiple days with millions of messages.

The leaks seem to be associated with structures allocation 'stdstrings' to save the "subject" and the "payload" for string based messages using send for amq.topic output.

Suggested work arounds are welcome based on application level changes to spout/drain (if they are missing key components) or changes to the address/setup of the queues for amq.topic messages (see the 'gospout.sh and godrain.sh' test drivers providing the specific address structures being used.

For example, the following is one of the 5 different categories of leaked data from 'spout.log' on a valgrind analysis of the output post the send and session.sync but prior connection.close():

==3388== 3,680 bytes in 10 blocks are still reachable in loss record 233 of 234

==3388==    at 0x4C2A203: operator new(unsigned long) (vg_replace_malloc.c:334)

==3388==    by 0x4EB046C: qpid::client::Message::Message(std::string const&, std::string const&) (Message.cpp:31)

==3388==    by 0x51742C1: qpid::client::amqp0_10::OutgoingMessage::OutgoingMessage() (OutgoingMessage.cpp:167)

==3388==    by 0x5186200: qpid::client::amqp0_10::SenderImpl::sendImpl(qpid::messaging::Message const&) (SenderImpl.cpp:140)

==3388==    by 0x5186485: operator() (SenderImpl.h:114)

==3388==    by 0x5186485: execute<qpid::client::amqp0_10::SenderImpl::Send> (SessionImpl.h:102)

==3388==    by 0x5186485: qpid::client::amqp0_10::SenderImpl::send(qpid::messaging::Message const&, bool) (SenderImpl.cpp:49)

==3388==    by 0x40438D: main (spout.cpp:185)