Fix compiler warnings.

Initialize all data members in initializer lists.
Reorder data members in initializer list to have the same order as in the class declaration.
Comment or remove unused parameters and unused variables.
Convert all old style casts to the correct and explicit c++ cast like const_cast, static_cast,
dynamic_cast or reinterpret_cast. In most cases static_cast is used.

examples/MQ/4-copypush/FairMQExample4Sampler.cxx

@@ -40,7 +40,7 @@ void FairMQExample4Sampler::Run()
 
         if (fChannels.at("data").size() > 1)
         {
-            for (int i = 1; i < fChannels.at("data").size(); ++i)
+            for (unsigned int i = 1; i < fChannels.at("data").size(); ++i)
             {
                 std::unique_ptr<FairMQMessage> msgCopy(NewMessage());
                 msgCopy->Copy(msg);