/cc @mapbox/games

Carrying over @springmeyer's comments from #7 (comment)

• Pass only a scaling value to decode geometries into tile coordinates: https://github.com/mapbox/vector-tile/blob/050da15c2af0e5b4c0b6459c4ebb61172b89e2a3/include/mapbox/vector_tile.hpp#L209
• As far as geometry storage, ignore my flat array comment - we do want easy to use, nested, arrays for parts following the lead of https://github.com/mapbox/geometry.hpp.

I've started the C# counterpart of geometry.hpp here: https://github.com/mapbox/GeometryCs

But we won't follow the C++ lead until geometry.hpp has fully found its way into vector_tile.hpp