Adding multiple transports support & other fixes:

- Avoid polling when only one input channel is used.
 - Send only handles for shared memory transport.
 - Avoid waiting in the rate logger thread when nothing to log.
 - Hide warnings from generated files
 - Fix #483

fairmq/FairMQMessage.h

@@ -18,6 +18,8 @@
 #include <cstddef> // for size_t
 #include <memory> // unique_ptr
 
+#include "FairMQTransports.h"
+
 using fairmq_free_fn = void(void* data, void* hint);
 
 class FairMQMessage
@@ -34,6 +36,8 @@ class FairMQMessage
 
     virtual void SetDeviceId(const std::string& deviceId) = 0;
 
+    virtual FairMQ::Transport GetType() const = 0;
+
     virtual void Copy(const std::unique_ptr<FairMQMessage>& msg) = 0;
 
     virtual ~FairMQMessage() {};