This fixes several refcount issues and not disconnected signal handlers for
EogWindow's GSettings handles.
- Due to some leaked references the window itself or its
EogThumbNavcould be prevented from finalizing. This would keep the GSettings bindings alive, which might cause a crash if the binding triggers
EogWindowuses standard signal handlers to connect
GActions to GSettings properties. If the GSettings handle was not finalized together with the window, these were not disconnected and could still trigger. As the window and its actions were gone this would crash. Fixes #291 (closed).