avoid cast warnings when compiling boost headers

src/ComputingTasks.cc

src/ConfigFile.cc

src/DataTree.cc

src/DynamicModel.hh

src/DynareMain.cc

src/DynareMain2.cc

src/MinimumFeedbackSet.hh

src/ModFile.cc

src/ModelTree.cc

src/ModelTree.hh

src/Statement.cc

src/StaticModel.hh

src/SymbolTable.cc