GDMLtoGM: adding handlers for <variable... />,<constant... />, <quantity......

GDMLtoGM: adding handlers for <variable... />,<constant... />, <quantity... />, which were initially forgotten

Changes to be committed: new file: GeoModelTools/GDMLtoGM/GDMLInterface/constantHandler.h new file: GeoModelTools/GDMLtoGM/GDMLInterface/variableHandler.h modified: GeoModelTools/GDMLtoGM/src/GDMLController.cxx new file: GeoModelTools/GDMLtoGM/src/constantHandler.cxx new file: GeoModelTools/GDMLtoGM/src/variableHandler.cxx

Thanks for this MR, @dellacqu. The pipeline is green: Ubuntu jobs were all green, macOS ones are flagged as orange/warning but I have checked and that was because of misconfiguration in the buildbot, where Eigen had to be re-installed. I have reinstalled it and that fixed the issue: I re-run a couple of the macOS jobs and they succeed fine.

Please let me know if you want me to make some other tests or if you want me to merge this.

Best, -- Riccardo.

mentioned in commit ee3f64d5

merged