TCPLink: use qobject_cast instead of dynamic_cast

qobject_cast is times faster dynamic_cast for objects that
inherit QObject. also, use auto keyword to not duplicate
class names.

src/comm/TCPLink.cc

@@ -280,7 +280,7 @@ TCPConfiguration::TCPConfiguration(TCPConfiguration* source) : LinkConfiguration
 void TCPConfiguration::copyFrom(LinkConfiguration *source)
 {
     LinkConfiguration::copyFrom(source);
-    TCPConfiguration* usource = dynamic_cast<TCPConfiguration*>(source);
+    auto* usource = qobject_cast<TCPConfiguration*>(source);
     Q_ASSERT(usource != NULL);
     _port    = usource->port();
     _address = usource->address();
@@ -326,7 +326,7 @@ void TCPConfiguration::loadSettings(QSettings& settings, const QString& root)
 void TCPConfiguration::updateSettings()
 {
     if(_link) {
-        TCPLink* ulink = dynamic_cast<TCPLink*>(_link);
+        auto* ulink = qobject_cast<TCPLink*>(_link);
         if(ulink) {
             ulink->_restartConnection();
         }