More functions to calculate the value of user columns

The features of user columns are extended with two new functions when defining calculation expressions in calculated user columns::

    Indicates the type of data contained in the cells of the user column represented by the parameter "n" (with a value between 1 and 15). The return value is "0" (contains text) or "1" (contains a numeric value).
    Returns the numerical value contained in the cell of the user column indicated by the parameter "n" (with value between 1 and 15). If the value of parameter 'n' is out of range, an error will occur and the text "Error" will be displayed in the cells of the column.