[Tagging] I started a draft on a new "main" key culture

[M∡rtin Koppenhoefer]

someone tried to change the meaning of culture=arts_centre by amending
the text to a meaning different of the one of amenity=arts_centre and
added also a new tag culture=community_arts_centre (without specifying
what this should be, but I guess it is our "good old" arts_centre).

Please do not do this in this proposal for a new culture key! Changing
the meaning of well established tags should go to another proposal.
This proposal is mainly about introducing a new key, and not about
redefining of already in use values.

I removed culture=community_arts_centre as I don't see the point in
it. We already have community centre and arts centre. If you want to
introduce new values, please elaborate on a definition and probably
make a different proposal for this change.

cheers,
Martin