Assign highway shield based on ref value

[Mashin6]

In some communities they have chosen to group all their roads under a single network value with an assumption that certain letter codes in ref would be sufficient to split them apart. An option would be to define shield graphics not only by an exact match of network, but also by an additional regex match in ref values.
This will have to be carefully crafted around ref preprocessing #141 in case it will be implemented.

Countries that are affected:
Hungary #69
Portugal
Bulgaria
North Macedonia

[1ec5]

In some communities they have chosen to group all their roads under a single network value with an assumption that certain letter codes in ref would be sufficient to split them apart.

As I understand it, the main reason for migrating to route relations with distinct networks was to keep data consumers from having to sniff out alphabetic codes the way they had been with refs on ways. It would be helpful to know the reasoning behind replicating the same unstructured format on relation refs. Maybe these communities could be convinced to make their route relation tagging more structured.

[Mashin6]

With Hungarian community that didn't work out.

There is also an option of not doing anything about it. It's all just a suggestion.

[claysmalley]

#355 #376 adds support for this, though regex matching is not implemented, so each ref=* with a special-case shield needs to be defined individually.

[ZeLonewolf]

My impression is that the countries listed have grouped together multiple de facto highway networks under a common network value, and that this is properly solved with a tagging solution rather than a rendering one. Thus, I agree with closing this issue upon merge of #355 #376, as the ask here "assign highway shield based on ref value" will be resolved. I don't think we should make special code for the case of insufficiently structured network tagging schemes.