a lot of work on process docs, and better error messages

corsika/detail/framework/process/InteractionProcess.hpp

corsika/detail/framework/process/ProcessSequence.inl

corsika/detail/framework/process/SwitchProcessSequence.inl

corsika/framework/process/BaseProcess.hpp

corsika/framework/process/BoundaryCrossingProcess.hpp

corsika/framework/process/ContinuousProcess.hpp

corsika/framework/process/DecayProcess.hpp

corsika/framework/process/InteractionProcess.hpp

corsika/framework/process/ProcessSequence.hpp

corsika/framework/process/ProcessTraits.hpp

corsika/framework/process/SecondariesProcess.hpp

corsika/framework/process/StackProcess.hpp

corsika/framework/process/SwitchProcessSequence.hpp

corsika/modules/StackInspector.hpp

tests/framework/testProcessSequence.cpp