Make figs includable in main document

Remove the capability to build them as standalone document but we can
include them in the main document.  It should simplify things down the
road.

book/figures/fig-liquid-starter-conversion.tex

@@ -1,6 +1,3 @@
-\input{./vars}
-
-\begin{document}
 \begin{tikzpicture}[node distance = 3cm, auto]
   \node [block] (init) {\footnotesize Make a regular or stiff starter};
   \node [block, right of=init] (feed_new_ratio) {\footnotesize Mix 1g existing starter, 5g flour and 25g water};
@@ -20,4 +17,3 @@
   \path [line] (ready_signs) -- node{\footnotesize yes} (last_feed);
   \path [line] (last_feed) -- node{\footnotesize after 6--12 hours} (bread_dough);
 \end{tikzpicture}
-\end{document}