Fix Distance3Dop geometries order

[piomar123]

Coordinates returned by Distance3Dop.nearestPoints() had a reversed order.
Additionally, the javadoc has been clarified to note that Distance3Dop does not interpolate Z ordinate which was not obvious.

[piomar123]

Maybe it would be better to create a separate method and deprecate the old one?

[dr-jts]

This looks good. Thanks for the patch.

[radi2015]

why different
Distance3DOp distance3DOp1=new Distance3DOp(g1,g2);
Distance3DOp distance3DOp1=new Distance3DOp(g2,g1);

code:
WKTReader wktReader=new WKTReader();
String wkt1="LineString Z (13520263.3311040997505188 3654113.41769909998401999 14.55408463999999924," +
" 13520263.98897077143192291 3654108.78580632992088795 14.56306395999999914," +
" 13520265.05638116039335728 3654101.43723948998376727 14.5861752899999999)";
String wkt2="LineString Z (13520262.04566529020667076 3654122.22497142991051078 14.53834022000000026, " +
"13520263.19403318502008915 3654114.04906051000580192 14.55408463999999924)";

Geometry g1 = wktReader.read(wkt1);
Geometry g2 = wktReader.read(wkt2);

Distance3DOp distance3DOp1=new Distance3DOp(g1,g2);
Coordinate[] coordinates1 = distance3DOp1.nearestPoints();
System.out.println(geometryFactory.createPoint(coordinates1[0]).distance(geometryFactory.createPoint(coordinates1[1])));
Distance3DOp distance3DOp2=new Distance3DOp(g2,g1);
Coordinate[] coordinates2 = distance3DOp2.nearestPoints();
System.out.println(geometryFactory.createPoint(coordinates2[0]).distance(geometryFactory.createPoint(coordinates2[1])));`
out:
0.6460693969920951
5.322947522798961