Zoom to location is disabled when the device is too far from the instance center, but the user is not informed

[jwalgran]

Taken from #319 (comment)

It's a bit surprising that if my location is not in the current treemap bounds then hitting the "zoom to my location" button does nothing. Ideally we'd display a message so indicating.

[maurizi]

For context: On the android app, while we do not start at the users current location if it is outside the map bounds, we always go to the users current location when they click the "zoom to my location" button.

[jwalgran]

The team discussed the issue and decided to copy the Android behavior.