Update references to TMS

[jyutzler]

Now that OGC has published the OGC Two Dimensional Tile Matrix Set Implementation Standard (see https://www.opengeospatial.org/standards/tms), we should update the GeoPackage ES to reference it.

[jyutzler]

As of today's SWG meeting, this is still an open issue. We're trying to sort out what actually needs to change.

[jyutzler]

I am now taking this on as part of the Vector Tiles Pilot Phase 2.

[jyutzler]

This is going to have to be its own extension. Pulling it out of 1.3.

[spatialillusions]

In OGC Two Dimensional Tile Matrix Set they still use the 0.28mm pixel size: "Cell sizes (pixel size in terrain units) are calculated assuming 0.28 mm pixel size and the WGS84 equatorial Earth diameter." I'm a bit unsure here about how do something for High DPI tiles, similar to @2x that you use for several online sources (see https://docs.mapbox.com/api/maps/) to get tiles that are suitable for High DPI screens. For sat images you can load another tile level on your High DPI device, to get a crisp image, but for raster maps, you will get labels that are tiny and unreadable if your do the same.