Adds initial intermediate qt6 porting state

qt6-after/qt6-migrated-legatus/Z/src/nglapplication/nglsingleapplication.h

@@ -0,0 +1,36 @@
+
+
+#pragma once
+
+#include <QtSingleApplication/QtSingleApplication>
+#include "nglloggerhandler.h"
+
+#ifndef NGLSINGLEAPPLICATION_EXPORT
+# ifdef BUILD_STATIC_LIBRARIES
+#  define NGLSINGLEAPPLICATION_EXPORT
+# else
+#  ifdef MAKE_NGLSINGLEAPPLICATION_LIB
+#   define NGLSINGLEAPPLICATION_EXPORT Q_DECL_EXPORT
+#  else
+#   define NGLSINGLEAPPLICATION_EXPORT Q_DECL_IMPORT
+#  endif
+# endif
+#endif
+
+namespace NGL
+{
+class INGLLogger;
+}
+
+class NGLSINGLEAPPLICATION_EXPORT NGLSingleApplication : public QtSingleApplication, public NGL::LoggerHandler
+{
+  Q_OBJECT
+
+public:
+  NGLSingleApplication(int &argc, char **argv);
+
+protected:
+  bool notify(QObject *o, QEvent *e) override;
+};
+
+#define nglApp static_cast<NGLSingleApplication*>(NGLSingleApplication::instance())