outdent: pad with trailing space to fixed with plus terminating characters

[samliddicott]

Please consider a feature where all lines are padded to the same length with spaces, and maybe trailing characters appended.

This means it easy to box text by using vertical box lines at either end of the line, especially in conjunction with #460

However boxing can be done externally if all lines are padded to the same width

[samliddicott]

Those outputting to terminal (and not to text file) can move the cursor to the right-column pad position $PAD_SIZE with:

tput el
tput cr
tput cuf ${PAD_SIZE}

and then emit whatever right-side bounding character they want