Submenu in a QMenu.

Adding a submenu to a QMenu is really easy, and you add nested submenus if you want:

```c
	QMenu* mainMenu;
	
	QAction* action1 = mainMenu->addAction(QIcon(":/icon1.png"),"Entry1" );
    connect( action1, &QAction::triggered,
                this, &MyClasss::mySlot1, Qt::UniqueConnection );

    QAction* action2 = mainMenu->addAction(QIcon(":/icon2.png"), "Entry2" );
    connect( action2, &QAction::triggered,
                this, &MyClasss::mySlot2, Qt::UniqueConnection );

	// --- SUBMENU --------------------------------------------------------
	
	QMenu* subMenu = mainMenu->addMenu( QIcon(":/menuIcon.png"), "SubMenu Title" );
	
	QAction* subAction1 = mainMenu->addAction(QIcon(":/subIcon1.png"),"subEntry1" );
    connect( subAction1, &QAction::triggered,
                   this, &MyClasss::subSlot1, Qt::UniqueConnection );

    QAction* subAction2 = mainMenu->addAction(QIcon(":/subIcon2.png"), "subEntry2" );
    connect( subAction2, &QAction::triggered,
                   this, &MyClasss::subSlot2, Qt::UniqueConnection );

	// --------------------------------------------------------------------
	
	
	QAction* action3 = mainMenu->addAction(QIcon(":/icon3.png"),"Entry3" );
    connect( action3, &QAction::triggered,
                this, &MyClasss::mySlot3, Qt::UniqueConnection );

    QAction* action4 = mainMenu->addAction(QIcon(":/icon4.png"), "Entry4" );
    connect( action4, &QAction::triggered,
                this, &MyClasss::mySlot4, Qt::UniqueConnection );
```