Add the ability to invoke custom GUI for a component

[grzesiek-galezowski]

This could be used to control the component in a different way or for custom monitoring.

[grzesiek-galezowski]

almost done - users can create custom GUIs. The only thing that's left is to register it on child-parent basis with the main UI

[grzesiek-galezowski]

to register with parent, plugin writers can use:
customGui.Owner = Application.Current.MainWindow;

Thus, this issue can be closed.