Possible broken paths in geometry loading

[Laurie Nevay]

Keeping as a note for myself.

"gdml:../path/to/a/file.gdml"

the path is expanded from the location of the main gmad file. If this is defined in sub-gmad file that isn't in the same directory as the main gmad file, the path would not be resolved correctly.

BDSGeometryFactory.cc uses BDS::GetFullPath from BDSUtilities.

[Laurie Nevay]

Fix Issue #147.

→ <<cset ae22a2475cc5>>