Add example with simple permalink support

This PR is still work in progress. For some reason the panning does not work (mouse cursor is always "finger" when the map is loaded)!?
Since this example is an evolution of the "map-extension" example, it might also be transfered in it.
If you're on a portal A, then change to the "map" page of that portal, and then navigate on the map, add layers etc. you will have to hit the browser "back" buttons many times to go back to the main portal page. I don't think that's what users expect. Users see the "map" page as an application, and they hit the browser back button they go back to the previous page, not the previous state of the "map" application. Don't you think so?