Dynare++: enforce C++ Emacs mode for bison/flex files

dynare++/parser/cc/assign.ll

dynare++/parser/cc/assign.yy

dynare++/parser/cc/csv.ll

dynare++/parser/cc/csv.yy

dynare++/parser/cc/formula.ll

dynare++/parser/cc/formula.yy

dynare++/parser/cc/matrix.ll

dynare++/parser/cc/matrix.yy

dynare++/parser/cc/namelist.ll

dynare++/parser/cc/namelist.yy

dynare++/src/dynglob.ll

dynare++/src/dynglob.yy