Rename qt generated variables for better readability

AdaptiveBrightness/main.cpp

@@ -4,8 +4,8 @@
 
 int main(int argc, char* argv[])
 {
-    QApplication a(argc, argv);
+    QApplication application(argc, argv);
-    AdaptiveBrightness w;
+    AdaptiveBrightness mainWindow;
-    w.show();
+    mainWindow.show();
-    return a.exec();
+    return application.exec();
 }