Reduce number of tiles in really pitched views by shifting horizon + use pitch in lod calculation

[karimnaaji]

reduce number of tiles in really pitched views

This view (#13.29/40.99611/-74.14597/-13.6/85) has 25 tiles:

On average each 512x512 tile is covering only 150x150. Reducing the number of tiles will reduce load time, memory usage and render times. Some possible ideas are:

• Move the horizon cutoff closer. There are some tiles that are only 3px vertically.
• Adjust the zoom calculation in the lod code to allow using even lower zoom tiles in the distance.

use pitch in lod calculation

The tile lod is based on distance to it's 3d cube. Tiles are mostly 2D. In pitched views tiles cover way less area. We should incorporate pitch into the lod calculation so that pitching more reduces tile zoom levels.

Suggestions by @ansis