Enhanced deegree for support of Spatial Joins

[dstenger]

This pull request implements support of "Spatial Joins".

A description how Spatial Joins work can be found in the WFS 2.0 specification: Chapter "7.9.2.5.3.1
Join queries", page 39

In addition, the implementation fulfils all requirements of the Spatial Joins conformance class as defined in the WFS 2.0 specification (Chapter "A.1.12 Spatial joins", page 103).

This is an example request how to use Spatial Joins:

<?xml version="1.0" encoding="UTF-8"?>
<wfs:GetFeature service="WFS" version="2.0.0" xmlns:app="http://www.deegree.org/app"
 xmlns:wfs="http://www.opengis.net/wfs/2.0" xmlns:fes="http://www.opengis.net/fes/2.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://www.opengis.net/wfs/2.0 http://schemas.opengis.net/wfs/2.0/wfs.xsd
http://www.opengis.net/fes/2.0 http://schemas.opengis.net/filter/2.0/filter.xsd"
 count="1">
 <wfs:Query typeNames="app:feature_type_1 app:feature_type_2">
  <fes:Filter>
   <fes:Intersects>
    <fes:ValueReference>app:feature_type_1/app:geometry</fes:ValueReference>
    <fes:ValueReference>app:feature_type_2/app:geometry</fes:ValueReference>
   </fes:Intersects>
  </fes:Filter>
 </wfs:Query>
</wfs:GetFeature>

In this case, an Intersect operation between the two FeatureTypes "feature_type_1" and "feature_type_2" is executed.
The result will be returned as a tuple.
Example of response:

<wfs:FeatureCollection xsi:schemaLocation="http://www.opengis.net/wfs/2.0 http://schemas.opengis.net/wfs/2.0/wfs.xsd http://www.opengis.net/gml/3.2 http://schemas.opengis.net/gml/3.2.1/gml.xsd http://www.deegree.org/app http://test-server:8080/deegree/services/wfs?SERVICE=WFS&amp;VERSION=2.0.0&amp;REQUEST=DescribeFeatureType&amp;OUTPUTFORMAT=application%2Fgml%2Bxml%3B+version%3D3.2&amp;TYPENAME=app:feature_type_1,app:feature_type_2&amp;NAMESPACES=xmlns(app,http%3A%2F%2Fwww.deegree.org%2Fapp)" timeStamp="2016-06-27T13:59:03Z" numberMatched="1" numberReturned="1" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:wfs="http://www.opengis.net/wfs/2.0" xmlns:gml="http://www.opengis.net/gml/3.2">
   <wfs:boundedBy>
      <gml:Envelope srsName="urn:ogc:def:crs:EPSG::4326">
         <gml:lowerCorner>...</gml:lowerCorner>
         <gml:upperCorner>...</gml:upperCorner>
      </gml:Envelope>
   </wfs:boundedBy>
   <wfs:member>
      <wfs:Tuple>
         <wfs:member>
            <app:feature_type_1 gml:id="feature_type_1_10" xmlns:app="http://www.deegree.org/app">
               <app:name>test</app:name>
               <app:geometry>
                  <!--Inlined geometry 'feature_type_1_10_APP_GEOMETRY'-->
                  <gml:Polygon gml:id="feature_type_1_10_APP_GEOMETRY" srsName="urn:ogc:def:crs:EPSG::4326">
                     <gml:exterior>
                        <gml:LinearRing>
                           <gml:posList>...</gml:posList>
                        </gml:LinearRing>
                     </gml:exterior>
                  </gml:Polygon>
               </app:geometry>
            </app:feature_type_1>
         </wfs:member>
         <wfs:member>
            <app:feature_type_2 gml:id="feature_type_2_3" xmlns:app="http://www.deegree.org/app">
               <app:name>test</app:name>
               <app:geometry>
                  <!--Inlined geometry 'feature_type_2_3_APP_GEOMETRY'-->
                  <gml:Polygon gml:id="feature_type_2_3_APP_GEOMETRY" srsName="urn:ogc:def:crs:EPSG::4326">
                     <gml:exterior>
                        <gml:LinearRing>
                           <gml:posList>...</gml:posList>
                        </gml:LinearRing>
                     </gml:exterior>
                  </gml:Polygon>
               </app:geometry>
            </app:feature_type_2>
         </wfs:member>
      </wfs:Tuple>
   </wfs:member>
</wfs:FeatureCollection>

The implementation is limited to PostgreSQL-FeatureStores.