GeoModel Updates, master branch (2020.03.11.)
This is meant as an extension/replacement for !618 (merged).
@rbianchi, there were a couple of things that I still noticed in your code while testing its build in some slightly non-standard scenarios. I thought it easiest to just make those changes myself.
Most importantly I noticed that GeoModelTools was only building correctly against an LCG release in your setup. I now added a XercesC package along with GeoModelTools as well, to make it possible to build VP1LightExternals without an LCG release being available for the build platform.