Go geometry/geography data types.

Features:

• Point, LineString, Polygon
• MultiPoint, MultiLineString, MultiPolygon
• *Z, *M, *ZM variants, including the Z and/or M coordinate.
• *S variants, including an SRID.
• null.* variants, to handle nullable SQL columns nicely.
• EWKB marshal/unmarshal.
• sql.Scanner, sql.Valuer implementation, tested with Postgres PostGIS.
• JSON marshal/unmarshal works nicely.