v4 preprocessor:

* renamed TmpSymbolTable to SymbolList (with some clean up by the way)
* removed unused mechanism of alternative variable names in tmp_var_list
* OptionsList: fixed memory leak and bug in clear()


git-svn-id: https://www.dynare.org/svn/dynare/dynare_v4@1785 ac1d8469-bf42-47a9-8791-bf33cf982152