add max-width option to DESCRIBE

[travv0]

Another proposal, this one will wrap the description text if the total line length is longer than max-width. Also fixes the padding for lines after the first line of the description being one character shorter than the first line's padding. Like my other pull request, I'll wait to update the tests until I know this is something you're actually interested in.

[travv0]

I added you as a collaborator so you can update add-text-padding to use your updated code. I believe we want (padding-next-lines (max 0 (1- padding))) to be (padding-next-lines (max 0 padding)) though or else each line after the first will be indented one less than the first line. Actually, looking at it again, I don't think we need a separate pad and pad-next-lines for anything, since I assume we'll always want all the lines aligned.