add setWindowFlags(Qt::Window) to improve window management

* improves window handling a lot
	(on Linux GNOME 3 at least: quickly resizing windows left/right, not forced in foreground anymore etc.)
	setWindowFlags() inserted in all *window.cpp files except mainwindow
    * some whitespace at EOL trimmed

re/flowviewwindow.cpp

@@ -12,6 +12,7 @@ FlowViewWindow::FlowViewWindow(const QVector<CANFrame> *frames, QWidget *parent)
     ui(new Ui::FlowViewWindow)
 {
     ui->setupUi(this);
+    setWindowFlags(Qt::Window);
 
     readSettings();