Fewer places at low zoom.

[zerebubuth]

The 0/0/0 tile contains:

• 91 countries,
• 744 regions,
• 25 localities.

We couldn't possibly render all of these in a single tile, so we should remove some of them. The properties on these features are the major contributor to size of tiles at zooms 3 and lower.

[nvkelso]

From #1684:

Let's use the min_zoom on country, region, and locality features from Natural Earth to drop labels.

In particular country labels don't all need to be shown at low zooms, just a few handful. There's a label min_zoom separate from feature min_zoom for this.

[nvkelso]

For 1/41/-74...

New:

Old:

[nvkelso]

0/43/-73

For zoom 0 we're still including too many countries, I'll file followup issue. Seems like we're doing 512 min_zoom math instead of 256 math? Like at zoom 0 we should only see features with min_zoom < 1, but many 1.x graded features are included.

New:

Old:

`

Similarly, Poland is visible at zoom 2, but has min_zoom of 3:

[nvkelso]

Generally this is working to significantly reduce file size... but we're still over stuffed. Followup in #1729.

For zoom 0 we're still including too many countries. The same is true for zooms 1 and 2. Addressing this will have significant file size savings.

Seems like we're doing 512 min_zoom math instead of 256 math? Like at zoom 0 we should only see features with min_zoom < 1, but many 1.x graded features are included.

New:

Old:

`
Poland is included at zoom 2, but it's min_zoom is 3.

[nvkelso]

Closing in favor of tiny bit of followup in #1729.