More PDF enhancements

Modernized the look and feel of the standard LaTex chapter titles and headers. Also tweaked the fonts a bit as I couldn't live without a serifed body font. Right now I'm using droid serif, sans, and sans mono for consistency. Yes, these fonts are designed for on-screen reading, but that's where I do most of my PDF reading anyways (plus it seems that most people will have those fonts on their linux boxes as I don't recall installing them).

Next up: margin notes for any markdown footnotes, which might be cool.