Initial implementation of cmdBINARY_ATTACHMENT which automatically split large messages into parts. Adapt cmdGET_LOG and cmdTRANSPORT_TEST for new implementation.  Still some problems with corrupted messages.
dds-protocol-lib: We need to make sure that write is not called from different threads. Only one write at time is allowed by asio. We therefore use conditional variable checks when calling syncWrite.
fixed: forgot to notify syncWrite about empty message queue.