Remove centering for floats (#364)

This was a bad idea...:
https://tex.stackexchange.com/questions/2651/should-i-use-center-or-centering-for-figures-and-tables

floatrows not sure how it should work with flowcharts... so we use
centring

I don't want to redefine all floats either as we use them for chapters
title page.

book/non-wheat-sourdough/non-wheat-sourdough.tex

@@ -17,14 +17,13 @@ a denser crumb compared to wheat, as you can see in
 Picture~\ref{fig:rye-crumb}.
 
 \begin{flowchart}[!htb]
-\begin{center}
+\centering
   \input{figures/fig-non-wheat-process.tex}
   \caption[Process for non-wheat sourdough bread]{A visualization of the
       process to make non-wheat sourdough bread.  The process is much simpler
       than making wheat sourdough bread. There is no gluten development. The
       ingredients are simply mixed together.}%
   \label{flc:non-wheat-sourdough}
-\end{center}
 \end{flowchart}
 
 For non-wheat flours---including rye, emmer, and einkorn---no gluten