Geometry enhancements.

1. Add altitude coordinate.
That involves adding 3-rd coordinate to the points in geometry and
implementing the set of functions to operate with it.

2. Convertors.
There is a lack of functions in MariaDB to export and import data
from/to various spatial data formats. So we need to implement functions
as
ST_GeomFromEWKB - ST_AsEWKB
ST_GeomFromGML - ST_AsGML
ST_GeomFromGeoJSON - ST_AsGeoJSON
ST_GeomFromKML - ST_AsKML

3. Getting data from SHP format.
It's good to have domesticated shp2sql convertor as
a separate tool and same functionality available inside the server
as the MariaDB SQL command.