move exam settings into a .settings object

I'm trying to clean up the model structure, with the aim of being more clear about the control flow, and being more explicit about state.
forgot to change some exam.settings references
Start integrating knockout

I'm having another go at using knockout to handle the view-model binding.
Knockout handles button presses and a few other bits at the moment. The aim is to end up having much more semantic HTML, and less spaghetti javascript responding to events and manipulating the DOM.
lots more knockout plodding; icon font

icon font is font-awesome: http://fortawesome.github.com/Font-Awesome/
update jQuery to 1.9.1
update runtime/readme with attributions

It was missing a lot of libraries, and I've switched the icons to font-awesome
remove a couple of unused things

uglifyjs pointed out some unused bits of code. I have arbitrarily picked some of them to remove.
update dates on copyright notices
update jquery UI

and jquery.impropmtu needed a change because $.browser was removed in jquery 1.9
yet more knockout stuff
part inputs bound to KO observables

Makes so many things easier!
Just need to finish off MultipleChoice parts
finish knockoutification of multiple response
(almost) all jQuery gone!

The JME preview is *so* much simpler in knockout.
All the jQuery event-binding and DOM manipulation that can be stripped out from display.js has been, apart from the question carousel - not sure if it's worth the effort to make a KO version.

Also moved the Reveal button down to the bottom, next to "Try another". I've been meaning to do that for a while.
remove repeated ids from HTML

I had been misusing ids for ages because I didn't know how things worked when I started Numbas.
Now styling for every element that occurs more than once is done through a class, not an id, like it should be.
update jquery.impromptu
reveal does not remove marks; show correct answer next to student's

The student does not lose their marks when they press Reveal. cf #233
The correct answer is shown next to the student's. cf #88
Still need to do a correct-answer display for MCQ parts.

New localisation string: 'part.correct answer'.

Finally, we're getting to the reason I started the knockout rewrite!
Next step: review mode.
show validation and tick/cross properly on reveal
clear up the markup for MCQs
starting on correct answer boxes for MCQs
all MCQ types have working correct-answer boxes