Merge pull request #772 from akohlmey/improved-variable-error-reporting

  void remove(int);

  void grow();

  void copy(int, char **, char **);

  double evaluate(char *, Tree **, int ivar=-1);

  double evaluate(char *, Tree **, int);

  double collapse_tree(Tree *);

  double eval_tree(Tree *, int);

  int size_tree_vector(Tree *);

  int compare_tree_vector(int, int);

  void free_tree(Tree *);

  int find_matching_paren(char *, int, char *&, int ivar=-1);

  int math_function(char *, char *, Tree **, Tree **, int &, double *, int &);

  int group_function(char *, char *, Tree **, Tree **, int &, double *, int &);

  int region_function(char *);

  int find_matching_paren(char *, int, char *&, int);

  int math_function(char *, char *, Tree **, Tree **,

                    int &, double *, int &, int);

  int group_function(char *, char *, Tree **, Tree **,

                     int &, double *, int &, int);

  int region_function(char *, int);

  int special_function(char *, char *, Tree **, Tree **,

                       int &, double *, int &);

                       int &, double *, int &, int);

  void peratom2global(int, char *, double *, int, tagint,

                      Tree **, Tree **, int &, double *, int &);

  int is_atom_vector(char *);