FastCaloSim: Making FastShowerCellBuilderTool const.
Change from IAtRndmGenSvc to IAthRNGSvc for MT-compatibility. Remove uses of gRandom.
Results change due to differences in how RNGs are seeded.
Change from IAtRndmGenSvc to IAthRNGSvc for MT-compatibility. Remove uses of gRandom.
Results change due to differences in how RNGs are seeded.