Add new KinBody::ExtraGeometryInfo struture for KinBody::Link::_mapExtraGeometries

[zax147]

Add support for serialization and deserialization of the extraGeometries field.

The extraGeometries in OpenRAVE is saved as std::map< std::string, std::vector<GeometryInfoPtr> > while the schema supposes to be:

         "extraGeometries": [
              {
                  "id": "extraGeometry_id",
                  "name": "extraGeometry_name",
                  "geometries": [
                      {
                          "id": "geom_id",
                          "name": "geom_name",
                      }
                  ]
              }
          ]