checkConnection verify connection both ways

The checkConnection() function previously only tested connectivity from
node->master. This modification tests connectivity node->master->node.
This should ensure proper maintenance of the mesh for new users and make
things less confusing. Behavior changes a bit, since the test is only
performed once, where previously, three attempts were performed.
#174 #165 #78

Author: TMRh20

RF24Mesh.cpp

@@ -138,21 +138,8 @@ void RF24Mesh::setChild(bool allow){
 /*****************************************************/
 
 bool RF24Mesh::checkConnection(){
-
-	uint8_t count = 3;
-	bool ok = 0;
-	while(count-- && mesh_address != MESH_DEFAULT_ADDRESS){
-        update();
-        if(radio.rxFifoFull() || (network.networkFlags & 1)){
-          return 1;
-        }
-        RF24NetworkHeader header(00,NETWORK_PING);
-		ok = network.write(header,0,0);
-		if(ok){break;}
-		delay(103);
-	}
-    if(!ok){ radio.stopListening(); }
-	return ok;
+    
+    return (getAddress(_nodeID) >= 0 ? true : false);    
 
 }