~| now incorporates the number of characters described so far

~| now incorporates the number of characters described so far

Therefore, subsequent uses of ~N| now yield the specified column,
instead of potentially overshooting.

Example:

    ?- format("hello~|~t~8|!", []).
    hello   !   true.

Such cases are probably rather uncommon: Relative positioning with ~N+
is more likely to be used in such cases, and that worked as intended
also previously as it does now:

    ?- format("hello~|~t~3+!", []).
    hello   !   true.

In fact, if absolute positions are used, then ~| can be omitted entirely:

    ?- format("hello~t~8|!", []).
    hello   !   true.