Add climbing features

[harahu]

Merge first: #1590

Description, Motivation & Context

Climbing is an activity that is often heavily reliant on maps and guides. Such material often exists in digital format, but the standard is, unfortunately, that information on climbing routes and areas are hidden behind paywalls. I want to contribute to making it more common that (geographic) information about climbing routes is shared in the open, and I think OSM is the obvious arena to do that.

The main barrier I currently see to sharing such information is that the beginner editor that newcomers to OSM reach for (iD) does not have any support for climbing related features. So I've decided I want to do something about that. I'll do that with this PR, as well as a subsequent PR to iD itself, if this PR goes though, where I'll improve rendering of climbing routes.

The climbing key today has ~26000 uses, so I think it deserves recognition in the editor.

Related issues

Links and data

Relevant OSM Wiki links:

• Climbing

Relevant tag usage stats:
https://taginfo.openstreetmap.org/keys/climbing#overview

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[tordans]

Lets see if we can keep the momentum of #1590 and this going, this time… :-). Here are some initial thoughts.

For the relation stuff – which I don't know a lot about – we should also look at #1538 to add some good validations and guidance to the UI (once that is merged…).

[harahu]

@tordans Thank you for the (very useful) review! I've now made this PR completely independent of #1590, so the order in which they are merged doesn't matter anymore.

If you're happy with this PR in it's current state feel free to merge it. Alternatively, I am considering splitting this PR into four different PRs (one per feature), such that we can discuss and merge them all individually.

[harahu]

@tordans: Closing this in favor of #1596, #1597 and #1598.