Add feature to create geometry from samplingGeometries for featureOfInte...

...rest if the featureOfInterest geometry == null:

- If the featureOfInterest geometry == null the SOS tries to query the samplingGeometries from the relatedObservations, ordered by phenomenonTime.
- If samplingGeometries are available, a gml:Point (one  samplingGeometry) or a gml:Curve (several samplingGeometries)  is created.
- If a two successive geometries have the same coordinates, the subsequent geometry is omitted.