Pedantic ch1 changes.

* Italicized "Learn You a Haskell..."
* Refactored the sectioning.
Add magit link in the contrib guide.
Add some macros for chapters and sections.
Switch to macros introduced in parent commit.
Add citation for LYAH.

This citation isn't particularly important, but it establishes the citation
format.
Chapter/section/paragraph prefix is now §.
Tweaks to the print-friendly links

* \href in the documents are now replaced with \link
* the emails on the title page now have mailto: links
Removed fontspec import.

No sense having pointless deps.
Well apparently fontspec wasn't pointless.