Use operator""s to replace some calls to std::string constructor

dynare++/parser/cc/atom_assignings.cc

dynare++/parser/cc/dynamic_atoms.cc

dynare++/parser/cc/fine_atoms.cc

dynare++/parser/cc/matrix.ll

dynare++/parser/cc/static_fine_atoms.cc

dynare++/src/dynare3.cc

dynare++/src/dynare_atoms.cc

dynare++/src/dynare_model.cc

dynare++/src/dynare_params.cc

mex/sources/bytecode/ErrorHandling.hh

mex/sources/bytecode/bytecode.cc

mex/sources/perfect_foresight_problem/DynamicModelCaller.cc

...es/perfect_foresight_problem/perfect_foresight_problem.cc

preprocessor