New draft for the flow-shop chapter.

Latest changes according to feedback from @mdibernardo and a completed chapter draft.
Noted, thanks. @MichaelDiBernardo -- any formal way to mark this as a section on the chopping block if space becomes an issue? In LaTeX I would just wrap it with a \hideifneedbe{} macro, but I'm not so familiar with the Markdown world to know what the best practice is...