replace auto& with auto const& in iterators when possible

...ework/random/random_iterator/detail/Random123/uniform.hpp

corsika/detail/framework/utility/QuarticSolver.inl

corsika/detail/modules/ParticleCut.inl

corsika/detail/modules/proposal/ContinuousProcess.inl

corsika/detail/modules/proposal/InteractionModel.inl

corsika/detail/modules/proposal/ProposalProcessBase.inl

corsika/detail/modules/pythia8/Decay.inl

corsika/detail/modules/sibyll/Decay.inl

corsika/detail/modules/sibyll/HadronInteractionModel.inl

corsika/detail/modules/tracking/TrackingLeapFrogCurved.inl

examples/cascade_examples/em_shower.cpp

examples/cascade_examples/radio_em_shower.cpp

examples/framework_examples/known_particles.cpp

tests/modules/testOnShellCheck.cpp

tests/modules/testParticleCut.cpp

tests/modules/testUrQMD.cpp

tests/output/testInteractionWriter.cpp