logic: file associations for Mac and opening project files via Mac OS

* hide start screen when opening with project file
* added project icon file to bundle and file type association to plist
* listen for file open events from double click or drag and drop
* fixed crashes in window handling

src/lib_gui/qt/window/QtMainWindow.cpp

@@ -62,8 +62,6 @@ bool MouseReleaseFilter::eventFilter(QObject* obj, QEvent* event)
 	{
 		QMouseEvent* mouseEvent = dynamic_cast<QMouseEvent*>(event);
 
-
-
 		if (mouseEvent->button() == m_backButton)
 		{
 			MessageUndo().dispatch();
@@ -82,7 +80,6 @@ bool MouseReleaseFilter::eventFilter(QObject* obj, QEvent* event)
 MouseWheelFilter::MouseWheelFilter(QObject* parent)
 	: QObject(parent)
 {
-
 }
 
 bool MouseWheelFilter::eventFilter(QObject* obj, QEvent* event)
@@ -106,6 +103,7 @@ bool MouseWheelFilter::eventFilter(QObject* obj, QEvent* event)
 	return QObject::eventFilter(obj, event);
 }
 
+
 QtMainWindow::QtMainWindow()
 	: m_showDockWidgetTitleBars(true)
 {
@@ -300,9 +298,9 @@ void QtMainWindow::popWindow()
 
 void QtMainWindow::clearWindows()
 {
-	if (m_windowStack.size())
+	for (QWidget* window : m_windowStack)
 	{
-		m_windowStack.back()->hide();
+		window->hide();
 	}
 
 	m_windowStack.clear();