Nicer/Simpler tables (#107)

* Make headrow in tables bold

* Simplify tables markup

- Markup is definitely simpler.
- Will not be built separately in a pdf anymore.
- Fixed some typo as well
- Relatively coherent look
- Can be better, some sizes are relatively arbitrary

* Remove horizontal separation inside tables

Not very nice if you ask me..

book/tables/vars.tex

@@ -1,2 +0,0 @@
-\documentclass{standalone}
-\usepackage{booktabs}