Series   first alternate

Hey Teresa.

Here's a quick fix for the issue you were having in this branch.  take a look at the code and let me know if you agree / have any questions.  This will work fine as-is but consider the note below.

navigation usually shouldn't be handled in the $_POST.  This means that the page state can't be bookmarked and the browser  back, next and reload buttons don't really work without reconfirming each submission.  Things like unit, series and especially user ids absolutely go in the POST - but things like page state (ex: which unit in the series) are better off in the GET.