Fix bug in scoring medium dose.

Query whether region is real (using app->isRealRegion(ir))
before including in medium dose.  Caused segmentation faults
for geometries in which default medium is not defined.

HEN_HOUSE/egs++/ausgab_objects/egs_dose_scoring/egs_dose_scoring.cpp

@@ -290,9 +290,11 @@ void EGS_DoseScoring::reportResults() {
  vector<EGS_Float> massM(nmedia,0);
  int imed = 0;
  for (int ir=0; ir<nreg; ir++) {
+ if(app->isRealRegion(ir)) {
  imed = app->getMedium(ir);
  EGS_Float volume = vol.size() > 1 ? vol[ir]:vol[0];
  massM[imed] += app->getMediumRho(imed)*volume;
+ }
  }
  if (normE==1) {
  egsInformation("\n\n==> Summary of media dosimetry (per particle)\n");