[Tagging] Proposal: Sunset ref=* on ways in favor of relations

[Andrew MacKinnon]

This seems reasonable.

It would be helpful if we changed the renderers to render the ref in a
route=road relation and ignore the ref tag if a route=road relation is
present. In Canada we had a problem a while ago with a user making
mechanical edits adding prefixes like "ON" and "RR" to a lot of roads.
I have been gradually deleting these prefixes but it is very time
consuming. Relations are a much better way of storing this data and if
renderers use the relation instead, then I could just delete these ref
tags instead of fixing them.