Brush up tst_QApplication

- Use nullptr
- Fix C-style casts
- Use range-based for
- Use correct static invocation
- Set a title on shown windows to make it possible to identify
  slow tests
- Fix the class declarations, use override, member initializations
- Use Qt 5 connection syntax; use lambdas where applicable
  to remove helper slots
- Streamline code in some cases
- Replace helper function to convert touch points by the one in
  QWindowSystemInterfacePrivate
- Use a logging category for the debug outpt, silencing some output

Change-Id: Ia46c7ad7c08f3afc8e5869ea99b66e406de97781
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@qt.io>

tests/auto/widgets/kernel/qapplication/modal/base.cpp

@@ -32,9 +32,8 @@ base::base(QWidget *parent) :
     QWidget(parent)
 {
     m_timer = new QTimer(this);
-    m_modalStarted = false;
     m_timer->setSingleShot(false);
-    connect(m_timer, SIGNAL(timeout()), this, SLOT(periodicTimer()));
+    connect(m_timer, &QTimer::timeout, this, &base::periodicTimer);
     m_timer->start(5000);
 }
 
@@ -43,6 +42,7 @@ void base::periodicTimer()
     if(m_modalStarted)
         exit(0);
     m_modalDialog = new QDialog(this);
+    m_modalDialog->setWindowTitle(QLatin1String("modal"));
     m_modalDialog->setModal(true);
     m_modalDialog->show();
     m_modalStarted = true;

tests/auto/widgets/kernel/qapplication/modal/base.h

@@ -37,12 +37,10 @@ class base : public QWidget
 {
 Q_OBJECT
     QTimer *m_timer;
-    bool m_modalStarted;
+    bool m_modalStarted = false;
-    QDialog *m_modalDialog;
+    QDialog *m_modalDialog = nullptr;
 public:
-    explicit base(QWidget *parent = 0);
+    explicit base(QWidget *parent = nullptr);
-
-signals:
 
 public slots:
     void periodicTimer();

tests/auto/widgets/kernel/qapplication/modal/main.cpp

@@ -26,8 +26,6 @@
 **
 ****************************************************************************/
 
-#include <QtGui>
-
 #include <QApplication>
 #include "base.h"
 
@@ -35,7 +33,6 @@ int main(int argc, char *argv[])
 {
     QApplication app(argc, argv);
     QApplication::setAttribute(Qt::AA_NativeWindows); //QTBUG-15774
-    base *b = new base();
+    base b;
-    Q_UNUSED(b);
     return app.exec();
 }