Map: generate pixmap name in model

Experimentation has shown that the image of a flag will
only be changed after dataChanged() if it is a simple
property. The old code had a complex QML expression and
then - for some reason - it didn't work.

To give us better control over the flags and avoid full
reloads of the map therefore introduce a model-property
pixmap name. The name depends on whether the site is
selected and if not, whether we are in divesite-edit mode.
This makes the code rather convoluted. Firstly, we have
to save whether the site is selected in the map-item.
Secondly we have to access the global map-widget, which
in turn has to go to the map-widget helper (layering
violation!).

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

desktop-widgets/mapwidget.cpp

@@ -79,6 +79,11 @@ void MapWidget::reload()
 	m_mapHelper->centerOnSelectedDiveSite();
 }
 
+bool MapWidget::editMode() const
+{
+	return isReady && m_mapHelper->editMode();
+}
+
 void MapWidget::selectedDivesChanged(const QList<int> &list)
 {
 	CHECK_IS_READY_RETURN_VOID();