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/makefile

@@ -28,10 +28,6 @@ export_figures:
 figures: clean_figures
 	cd figures && find . -name "fig-*.tex" -exec pdflatex '{}' \;
 
-.PHONY: tables
-tables:
-	cd tables && find . -name "table-*.tex" -exec pdflatex '{}' \;
-
 .PHONY: clean
 clean: clean_figures
 	rm -f book.blg