Fix some issues detected by Clazy (#384)

* Fix old style connect

* Fix unneeded QString memory allocations

src/widgets/loadspinner.cpp

@@ -32,7 +32,7 @@ LoadSpinner::LoadSpinner(QWidget *parent) :
     updateFrame();
     // init timer
     m_timer =  new QTimer(this);
-    connect(m_timer, SIGNAL(timeout()), this, SLOT(rotate()));
+    connect(m_timer, &QTimer::timeout, this, &LoadSpinner::rotate);
     m_timer->setInterval(30);
 }