Low level GeoJson implementation

This is a request for either a rewrite or alternative implementation of the current GeoJson module found here. We need a high performance implementation that has a minimal memory footprint. The reasoning behind that is that geojson models should be scalable (eg. downstream we query the map for 1000 of features, the path currently taken to create those and the intermediate objects created for doing that isn't optimal atm).

Couple of thoughts to improve this:

• use primitive instead of objects where possible
• no need for AutoValue, implementation is based on a specification that doesn't change (often)
• if geojson models are immutable, use arrays instead of List
• limit method invocations & don't allocate memory if you can avoid it
• don't over abstract concepts if they can be expressed more simple

More information on performance tips here
RFC of GeoJSON can be found here.

cc @mapbox/android

先檢視 services-geojson 中目前的實作，接著將其模型結構與 RFC 7946 以及連結的 Android 效能提示進行比較。定義重寫版本或替代方案將如何針對約 1,000 個 features 測量記憶體使用量和效能；當 GeoJSON 模型在沒有不必要的配置或抽象的情況下達到所要求的擴充性目標時，即表示完成。