Add GeoMaterial and GeoElement support to GeoExporter and clean DumpGeo
This MR completes the mechanism to dump the full GeoModel tree to a local file. It adds the missing support for GeoElement objects, to get a full persistent copy of all GeoMaterial and GeoElement nodes.
In addition, this MR cleans up the code of DumpGeo, to get rid of FileIncidents listeners.
Tagging @tsulaia for info.
Edited by Riccardo Maria Bianchi