Converts the given meshes into CityObjects.
The CityGML object type is set to the value of the gml:type attribute of the mesh
(or Building if not set).
The LOD is set to the value of the bldg:lod attribute of the mesh (or 2.0 if not set).
The geometry type can be set by the value of the gml:geometryType attribute of the mesh
(possible values: Solid, MultiSurface). By default, it is set to Solid.