Utf 8 62519814

This PR adds better UTF-8 support. In particular, you can now do things like 
```latex
\title{A könyv címe}
\subtitle{Alcím - itt lesz az alcím}
\author{Árvíztűrő fúrógép}
\date{January 1, 2013}
```
(or equivalently in `book.yml`). You can also define a new word for "Chapter" in `custom.sty` as follows:
```latex
\renewcommand{\chaptername}{Chapitre}
```
This yields output in the book like this:
```
Chapitre 1
```