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.
`$location` is already injected in the outer function, so you don't need to inject it here again. And also, I'm not sure injection will work here when the example is compiled.