Don't ignore contradictory *:surface=* and surface=* tags

[Discostu36]

Use case
When SC asks for footway:surface=* and cycleway:surface=* on a segregated highway=path, it does not change surface=*, even when it is contradictory.

See for example this path.

biclycle	designated
cycleway:surface	paving_stones
foot	designated
footway:surface	paving_stones
highway	path
segregated	yes
surface	asphalt

Proposed Solution
Three possibilities (in ascending effort):

1. StreetComplete should delete a mismatching surface=* tag
2. StreetComplete should change it according to footway:surface and cycleway:surface, but only if both are the same
3. StreetComplete should also change surface=* tag if footway:surface and cycleway:surface are not the same, but both are paved or unpaved (for example footway:surface=paving_stones and cycleway:surface=asphalt → surface=paved). If one way is paved and the other one unpaved, it should add them via semicolon (e.g. surface=asphalt;dirt).

[mnalis]

Make sense to me.

If someone wants to give it a try, leave a comment stating so.
(if noone steps up, I can give it a try in few days, for option 2 with fallbacking to 1)

[Discostu36]

One thing I forgot about is that options 2 and 3 of course could also be used to add missing surface tag, not only change it.

[RubenKelevra]

One thing I forgot about is that options 2 and 3 of course could also be used to add missing surface tag, not only change it.

Nah, if there are two explicit surface information, I would keep them both. Explicit is always better than implicit IMHO. For example that could be the only part of the way which has the same surface and in the next part they differ again.

With just one tag I would second guess if the information is complete for this part.

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But the surface tag feels kinda superficial, if both parts of that way are already tagged individually.

[mnalis]

Nah, if there are two explicit surface information, I would keep them both. Explicit is always better than implicit IMHO

Agreed, but if I understood @Discostu36 correctly (hopefully I did, as i did the PRs 😄), it would keep both of them, and then add surface too. E.g. final result of such tagging would be:

cycleway:surface=asphalt
footway:surface=asphalt
surface=asphalt

and not just:

surface=asphalt

[Discostu36]

@mnalis You understood my intent correctly. It is a bit redundant, but I think it is the best solution.