public double get_double (string group_name, string key) throws KeyFileError
Returns the value associated with
group_name as a double.
group_name is null, the start_group is used.
key cannot be found then 0.0 is returned and throws is set to
KEY_NOT_FOUND. Likewise, if the value associated with
cannot be interpreted as a double then 0.0 is returned and throws is set to
a group name
the value associated with the key as a double, or 0.0 if the key was not found or could not be parsed.