Allow Z_ORDER_LAT_LON to apply to either one or two columns.
Added more tests of Z_ORDER_LAT_LON with one argument.
merge geophile: Allow Z_ORDER_LAT_LON to apply to one column

Merge pull request #138 from geophile/sql-parser/geophile-integration
https://github.com/FoundationDB/sql-parser/pull/138