GSI

Implementation of a map tile retriever for "Chi-ri-in-tile" ("地理院タイル"; ja-JP) of "Geospatial Information Authority of Japan" (GSI).

Features

Tile
- [x] Get a blob Vec<u8> of a tile using id, x, y, z, ext and params.
- [x] Get a image image::DynamicImage of a image tile.
- [x] Get a altitudes Vec<f64> of a DEM(.png; GSJ-Nishioka-Nagatsu-2015) tile.
- [x] Get a altitudes Vec<f64> of a DEM(.txt; CSV) tile.
[cocotile]
- [x] Get a tile-ids as Vec<String>.
[Layers.txt]
- [x] Get a Layers.txt as Layers.
  - [x] Layers type = Layers.txt; {"layers":[{...},...]}
  - [x] LayerVariant type = enum of Layer | LayerGroup
  - [x] Layer type and LayerGroup type = entry of "type":"Layer" | "type":"LayerGroup"
- [x] Make/Store/Load CachedLayers (=HashMap<String, Layer>) feature for local Layer informations caching
  - [x] Retrieve the other Layers.txt source file of "src" external referencing in Layer
    - [x] Explicit enabling/disabling switching
  - [x] .to_json_string, .to_json_vec; serdejson syntax sugar for storing a local Layer informations cache
  - [x] .from_json_string, .from_json_slice; serdejson syntax sugar for loading a local Layer informations cache

These files are GSI's tiles. It's for only to use unit tests, no need essentially.