These functions change the names of variables within a dictionary.
var_set_name function (see var_set_name) cannot be
applied directly to a variable that is in a dictionary, because
struct dictionary contains an index by name that
would not update. The following functions take care to update the
index as well. They also ensure that variable renaming does not cause
a dictionary to contain a duplicate variable name.
Changes the name of var, which must be in dict, to new_name. A variable named new_name must not already be in dict, unless new_name is the same as var's current name.
Renames each of the count variables in vars to the name in the corresponding position of new_names. If the renaming would result in a duplicate variable name, returns false and stores one of the names that would be be duplicated into
*err_name, if err_name is non-null. Otherwise, the renaming is successful, and true is returned.