Nicer tables episode II (#111)

* 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..

* Fix some tables for the ebook

The alignement trick to have nicely alignment on = sign or on unit (g)
used broke the html. Reverting to a less optimal version on pdf while
not breaking the html.

* Simplify table for html output

* Revert "Simplify table for html output"

This reverts commit f85d65adb7.

* Revert pancake table

This way it builds ebook correctly.

book/book.tex

@@ -13,6 +13,10 @@
 \usepackage{tocloft}
 \usepackage{tex4ebook}
 \usepackage{chemformula}
+\usepackage{booktabs}
+\usepackage{makecell}
+
+\renewcommand\theadfont{\bfseries}
 
 % Fonts for accessibility
 %\usepackage{helvet}