Finished implementation of new data representation for tiles;

- Renamed jsonExtractor to geoJson;
- Removed use of JSON everywhere except geoJson and MapzenVectorTileJson;
- Used glm::vec3 as basis of common coordinate data;
- Updated documentation of tileData.h;
- Modified geometry construction pipeline to produce geometry with coordinates normalized to the size of the enclosing tile (see tileData.h)