Fix our Jackson ShapeDeserializer for 3rd dimension (#224)

Author: hauke96

src/main/java/org/locationtech/spatial4j/io/jackson/ShapeDeserializer.java

@@ -44,7 +44,7 @@ public Point readPoint(ArrayNode arr, ShapeFactory factory) {
     double x = arr.get(0).asDouble();
     double y = arr.get(1).asDouble();
     if(arr.size()==3) {
-      double z = arr.get(3).asDouble();
+      double z = arr.get(2).asDouble();
       return factory.pointXYZ(x, y, z);
     }
     return factory.pointXY(x, y);
@@ -57,7 +57,7 @@ private void fillPoints( ShapeFactory.PointsBuilder b, ArrayNode arrs ) {
       double x = arr.get(0).asDouble();
       double y = arr.get(1).asDouble();
       if(arr.size()==3) {
-        double z = arr.get(3).asDouble();
+        double z = arr.get(2).asDouble();
         b.pointXYZ(x, y, z);
       }
       else {
@@ -232,4 +232,4 @@ public Shape deserialize(JsonParser jp, DeserializationContext ctxt)
     }
     throw new JsonParseException(jp, "can't read GeoJSON yet");
   }
-}
+}