Save changes when toggling checkboxes in ExportDialog

Save changes when toggling checkboxes in ExportDialog

I used the Widget::on_hide method in the ExportFileDialog to defer the saving
of changes in state of the analysis and soundcloud-upload checkboxes as it was
not possible to save the format xml state directly from the
ToggleButton::toggled() signal as it created a recursive loop and also to
prevent saving the state more than once.

Even though the ExportProfileManager::FormatListChanged signal is no longer
emitted when saving format state and the crash no longer occurs without this
change. I think it is worth saving explicitily from in the toggle callbacks to
reduce the complexity of understanding what is taking place and when even if it
is less efficient.

There is definitely more opportunity for refactoring and redesign.