Add a 'Zoom in to Edit' button to mirror openstreetmap.org

[mikejeffe]

Seems like a relatively simple and benign feature to add. In addition to the warnings indicating that you need to Zoom in to edit a feature, have a nice big button that zooms to the appropriate zoom level to start editing a feature similar to how the openstreetmap.org iD version does it.

[mikejeffe]

The button goes away when you hit the editable zoom level.

[sisskind]

@mjeffe98 does it zoom in incrementally or to the editable zoom level?

[mikejeffe]

@sisskind it zooms to the editable zoom level.