Add ST_XYZMinMax

This is basically the equivalent of irstv/orbisgis#272.

I included GDMS's [CoordinatesUtils](https://github.com/irstv/orbisgis/blob/0c5127db546286a245fe6a490b4e035659ebca2a/gdms/src/main/java/org/gdms/geometryUtils/CoordinatesUtils.java) class in order to be able to use the `zMinMax` method.