Restore the view state after the URL of the DolphinView has been changed,

Restore the view state after the URL of the DolphinView has been changed,
as stated in the documentation of KUrlNavigator::saveLocationState.

The historyChanged signal of the KUrlNavigator is emitted before the urlChanged
signal and so the view state restoring happens before the view URL has been
changed. This makes it impossible to save and restore the selected URLs, because
DolphinView::setUrl clears the list of selected items (which has been restored
right before). This changes removes the history changed slot and restores the
view state after the setUrl call.