Add whitespace around headers for readability
Add first attempt at title
Remove reference to adding blanks when models didn't converge

This is an implementation detail that isn't necessary in the methods.
Edit Introduction

The goal of these edits is to make the Intro concise and have it focus
on the big picture goals. I have moved some material down to the
Discussion so we can consider adding it there and flagged another
section for possible removal with a comment.
Proper citation for Ulrich paper is Ulrich et al. 2010
Add introductory paragraph for Data section of Methods
Move description of changes to Gentry sites into Gentry section
Move section on Models before section on Analysis
Edits to Models section
Edits to the Analysis section
Comments adding thoughts and suggestions
Merge pull request #57 from ethanwhite/ch1-edits

Looks good on a quick comparison.