move files to src directory

src/CodeInterpreter.hh

src/ComputingTasks.cc

src/ComputingTasks.hh

src/ConfigFile.cc

src/ConfigFile.hh

src/DataTree.cc

src/DataTree.hh

src/Doxyfile

src/DynamicModel.cc

src/DynamicModel.hh

src/DynareBison.yy

src/DynareFlex.ll

src/DynareMain.cc

src/DynareMain1.cc

src/DynareMain2.cc

src/ExprNode.cc

src/ExprNode.hh

src/ExtendedPreprocessorTypes.hh

src/ExternalFunctionsTable.cc

src/ExternalFunctionsTable.hh