[cleanup] removed Dune::Exceptions from main files

exercises/exercise-basic/2p2cmain.cc

exercises/exercise-basic/2pmain.cc

exercises/exercise-biomineralization/main.cc

exercises/exercise-coupling-ff-pm/interface/main.cc

exercises/exercise-coupling-ff-pm/models/main.cc

exercises/exercise-coupling-ff-pm/turbulence/main.cc

exercises/exercise-fluidsystem/main.cc

exercises/exercise-fractures/main.cc

exercises/exercise-grids/main.cc

exercises/exercise-mainfile/exercise1pamain.cc

exercises/exercise-mainfile/exercise1pbmain.cc

exercises/exercise-mainfile/exercise1pcmain.cc

exercises/exercise-properties/main.cc

exercises/exercise-runtimeparams/main.cc

exercises/solution/exercise-basic/2pnimain.cc

exercises/solution/exercise-biomineralization/main.cc

exercises/solution/exercise-coupling-ff-pm/interface/main.cc

exercises/solution/exercise-coupling-ff-pm/models/main.cc

...cises/solution/exercise-coupling-ff-pm/turbulence/main.cc

exercises/solution/exercise-fluidsystem/main.cc