[oscon] overlays in place; dns perf and backgrounds to do
[git] ignore osx droppings
[oscon13] slides just about done, background and dns perf to go
[oscon13] alternate fonts, local copies
[oscon13] overall slide sizes and related layout fixes
[oscon13] logos
[oscon13] colour and relabel plots
[oscon13] finish first pass, all figures, logos, numbering
[oscon13] tweaking slide ordering, title meta etc