Followups from PR #47 and additional polish

Includes minor polish and bug fixes to #47

[x] Country labels at early zooms with CountryInfo functionality and tests
- [x] Bug fixes
[x] Region labels at early zooms with RegionInfo functionality and tests
- [x] Bug fixes
[x] More locality labels at early zooms
[x] Consistent locality labels at mid zooms (San Francisco was popping in and out versus Oakland)
- [x] Bug fixes
[x] Remove WOF reference from SemVer statement as that's not used yet
[x] Minor style changes / bug fixes
[x] Add Makefile target for Kansas (helpful for debugging country and region labels in USA)
[x] Add Makefile target for planet-xl for super well provisioned machines (and twiddle planet target)
[x] Switch countryInfo to ISO codes (instead of fussy names) && update test
[x] Switch regionInfo to ISO codes (instead of fussy names) && update test
[x] Physical lines always set pmap:level, not just at late zooms
[x] Places add sortKey and label grid for more consistent labeling (and smaller tiles)
[x] POIs show smaller park labels at slightly earlier high zooms
[x] POIs discount tall self storage buildings
[x] POIs discount very long text names should only be shown at later zooms
[x] POIs emphasize IATA airports
[x] POIs de-emphasize wilderness areas
[x] Transit include pmap:min_zoom for client side label collisions
[x] Transit always set pmap:level, not just at late zooms
[x] Don't use 110m Natural Earth data ever (use 50m instead at lowest zooms)
[x] Boundaries from NE show 1 zoom earlier (confusing 256px versus 512px bug)
[x] Water from NE show 1 zoom earlier (confusing 256px versus 512px bug)
[x] OSMRef option to gather localized refs (like OSMNames) for Places layer
[ ] Push some small zoom 14 parks in POIs layer to zoom 15 / 16 instead

In my rush out the door for vacation and then funeral I had a few uncommitted local changes that are recreated here on top of latest main.

protomaps / basemaps

Followups from PR #47 and additional polish #79