Plugins: Add support for other tiled formats

[gkjohnson]

• QuantizedMesh tiles for rendering ion terrain
  • https://github.com/CesiumGS/quantized-mesh
• WMTS tiles for rendering 2d map data
  • Can support planar or ellipsoid projection
  • https://api.oneatlas.airbus.com/guides/oneatlas-basemap/g-oab-wmts-basic/
  • https://opengeospatial.github.io/e-learning/wmts/text/main.html
• OpenSeadragon for rendering high resolution images
  • https://openseadragon.github.io/
• OpenStreetMap data
  • Possibly using WMTS? Also provides vector tiles
  • https://wiki.openstreetmap.org/wiki/Tiles

Notes

• All implementations can use implicit tiling for the tile hierarchy.
• Implicit tiling will expand every tile out into a JSON object when it doesn't have to be. Could possibly support some kind of "virtual" children that are pooled and initialized on usage, then reset every update. Then only as many tile objects as are needed for a single traversal are created.