Apologies for the deluge of tiny commits. It's late and I'm incompetent.

Moved the commit button to the top of the list in a tfoot tag so that it appears even when there are errors

add a new function to save a message flash in the session data to be displayed on the next page load (e.g. when we're doing post/redirect/get)

alomst finished signup system, all the logic is there, just need to be made to look nice and the deplyment TODOs followed

signup system now generates ldifs, and adds members to the mailing lists, dont forget to remove the dev mods before deploying

UI and validation for the new signup system, actual backend functionality is started but mostly missing

Makes password check function in session class public

fix some more session weirdness by deleting loggedin cookies instead of piling them up on top of each other

timeout anonymous sessions earlier, to stop the session table getting massive. And fix the inevitable stupid bug which crept in