Add adm0_type flag for promoting, demoting motorways

[nvkelso]

Propose 3 types of road based on the general coding scheme in that administrative unit (countries, states in the US).

Some countries like the UK have a surplus of motorway and trunk class roads. Others, especially outside of western Europe, have a well connected road network, but that's not reflected in the highway type attributes. San Francisco is mostly good. New York could have a few promotions.

Based on the adm0_type flag, the view would promote or demote ways on the edge of a major - mid class boundary.