Book line length

Went through all the code to fix most occurrences of long line length. In general, that means that lines that are visible in the book are 58 characters long. If they're outdented in the book (e.g. a snippet from within a function) then they can be 60 characters long.

In a few cases, I kept a line that was 1 or 2 characters too long because dividing it would be ugly, and the natural break wasn't too bad looking.

This pull request is matched by a CL with corresponding fixes to the text: https://chromiumcodereview.appspot.com/812553007/