Add serializers back into ByteString

[tysonzero]

It would be ideal if I could freely convert between geojson and ewkb in both directions. Specifically I need my Haskell backend to add new data to PostGIS, not just parse and use existing data.

[newmana]

Good idea. It would be good for testing too.

[newmana]

Hi, we've made some progress on this. But on the way we discovered that wkt, wkb and geojson all have slightly different features that make hard. As long as you stay within 2d and 3d points that are all the same type.

[newmana]

See issue #8