Support empty point in WKB

[newmana]

"Well-Known Binary as defined in ISO 13249-3 [12] does not provide a standardized encoding for an empty point set (i.e., Point Empty in Well-Known Text). In GeoPackages these points SHALL be encoded as a Point where each coordinate value is set to an IEEE-754 quiet NaN value."

https://gis.stackexchange.com/questions/109889/wkt-what-is-the-reasoning-behind-the-concept-of-a-point-empty