Added readme on new features on doc/

doc/README_newFeatures.txt

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+/********/
+Internal ePRosima doc - New features in this branch
+/********/
+
+--- Query the number of Publishers and Subscribers listening to a topic
+
+Participant has 2 new API functions, get_no_publishers and get_no_subscribers
+These functions a target_topic as argument and return the number of pubs/subs
+that exist on a participant that are assigned to the specified topic
+
+--- Possibility to attach a secondary ReaderListener to SimpleEDP RTPSReaders
+
+A new Participant API function, getEDPReaders, allows the user to get pointer
+to the two stateful readers the EDP spawns. From here it is possible to access
+the ReaderListener, which has been modified.
+
+The ReaderListeners used in the EDP Readers inherit from a class that allows a
+slave ReaderListener to be attached. This way a user can attach his own
+ReaderListener so that its callback is executed whenever the default EDP
+callback is invoked. 
+
+The result of this is that there is a path from user land to the EDP
+RTPSReaders, then to the modified ReaderListener and from there we can
+attach a user defined ReaderListener with its own callbacks.
+
+--- Examples:
+
+	---Attach a slave ReaderListener:
+	- The target slave ReaderListener inherits from ReaderListener
+
+class gettopicnamesandtypesReaderListener:public ReaderListener
+{
+	public:
+	std::mutex mapmutex;
+	std::map<std::string,std::set<std::string>> topicNtypes;
+	void onNewCacheChangeAdded(RTPSReader* reader, const CacheChange_t* const change_in){
+		CacheChange_t* change = (CacheChange_t*) change_in;
+		if(change->kind == ALIVE){
+			WriterProxyData proxyData;
+			CDRMessage_t tempMsg;
+			tempMsg.msg_endian = change->serializedPayload.encapsulation == PL_CDR_BE ? BIGEND:LITTLEEND;
+			tempMsg.length = change->serializedPayload.length;
+			memcpy(tempMsg.buffer,change->serializedPayload.data,tempMsg.length);
+			if(proxyData.readFromCDRMessage(&tempMsg)){
+				mapmutex.lock();
+				topicNtypes[proxyData.m_topicName].insert(proxyData.m_typeName);		
+				mapmutex.unlock();
+			}
+		}
+	}
+};
+
+	- Insertion  from within application code:
+
+std::pair<StatefulReader*,StatefulReader*> EDP_Readers = my_participant->getEDPReaders();
+	InfectableReaderListener* target = dynamic_cast<InfectableReaderListener*>(EDP_Readers.second->getListener());
+	target->attachListener(slave_listener);
+	result = target->hasReaderAttached();
+	ASSERT_EQ(result,true);
+	slave_target =  dynamic_cast<gettopicnamesandtypesReaderListener*>(target->getAttachedListener());
+
+
+	--- Poll the no of Pubs and Subs on topic "TEST_NAME"
+
+std::string my_topicName("TEST_NAME");
+int no_pubs = my_participant->get_no_publishers(my_topicName.cstr());
+