`char_type` `lower` seems broken

On the docs: ``` ?- char_type(a, Type). Type = alnum ; Type = alpha ; Type = alphabetic ; Type = alphanumeric ; Type = ascii ; Type = ascii_graphic ; Type = hexadecimal_digit ; Type = lower ; Type = octet ; Type = prolog ; Type = symbolic_control ; Type = lower("a") ; Type = upper("A") ; false. ``` On master: ``` ?- char_type(a, X). X = alnum ; X = alpha ; X = alphabetic ; X = alphanumeric ; X = ascii ; X = ascii_graphic ; X = hexadecimal_digit ; X = lower ; X = octet ; X = prolog ; X = symbolic_control ; X = lower("A") %what? ; X = upper("A") ; false. ```