(Bug 4902) Tectonic - new layout by momijizukamori + spire, with five co...

...lor themes and optimized preview images

I think I got the biggest mistakes (care of having them pointed out on other patches!) but the file needs a good one-over, at the very least. I've checked it in Chromium and Firefox for Linux; all the CSS *should* be compliant with Safari and IE down to 7 or so at least.