FHCal geometry macro fix
Small fixes to the FHCal geometry macros were added:
- macro/mpd/geometry/create_rootgeom_zdc_oldnames_7sect_no_central_module_v1.C: cleared unnecessary comments and obsolete descriptions compared to the older macro. Material inside scintillators in FHCal modules have been changed from FscScint to the polysterene which is closer to the real one used in FHCal.
- Added WALL geometry file macro/mpd/geometry/create_rootgeom_wall_vacuum_no_hole_oldnames_v1.C