Make SetMaterials method from FairRunSim available in FairRunAna as well

[mgoncerz]

The method FairRunSim::SetMaterials, which allows to set the name of file containing media information, is currently available only if using FairRunSim, but not in FairRunAna. It would be useful to have it there as well, because material information is sometimes necessary even if not running generation step (for example to extract radiation length for multiple scattering correction). This should be coupled with creating an instance of FairGeoLoader (it isn't when using FairRunAna) and doing:

static FairGeoInterface* geoFace = geoLoad->getGeoInterface();
geoFace->setMediaFile(name);
geoFace->readMedia();

somewhere in the code, so that a piece of code like:

media = geoFace->getMedia();
medium = media->getMedium(material name);
medium->getRadiationLength();

can be used directly from a FairTask.