Add the layer= tag to the editor presets

[bborkmiller]

It would be handy to have a dedicated field for the layer= tag, rather than have it buried down in the "All tags" section. It would be handiest if it the value of the layer tag showed up in the Structure box, since it's most likely to be used in conjunction with a bridge or tunnel.

[talllguy]

This could also be an option somewhere, to show or hide the extra tags section at all times.

[bhousel]

There is a layer field, but it seems to only show for waterway=stream... Which unfortunately is one of the places that it isn't needed.

I could see it being added to the structure box - and maybe have it only pop up if the user picked tunnel or bridge... That might be best.

[Codain]

I tag man_made=bridge a lot and it is tipically something missing.

It can be displayed as soon as one of those tags are set:

• man_made=bridge
• bridge=* (with a value different from 'no')
• tunnel=* (with a value different from 'no')
• layer=* (as already the case I assume)

Which also means that if I manually add one of those tags I would expect this field to be automatically shown.

[bhousel]

This was done in #3911