Fix links colors (#144)

* Add chemfig package

Somhow forgot it in chemical equation commit 8004497b

* Change links colors to codeblue

Closes https://github.com/hendricius/the-sourdough-framework/issues/142

book/book.tex

@@ -11,6 +11,7 @@
 \usepackage{tocloft}
 % \usepackage{tex4ebook}
 \usepackage{chemformula}
+\usepackage{chemfig}
 \usepackage{booktabs}
 \usepackage{makecell}
 \usepackage{siunitx}
@@ -42,7 +43,8 @@
 % Clickable links in the table of contents
 \usepackage[ocgcolorlinks]{hyperref}
 \hypersetup{%
-    linktoc=all
+    linktoc=all,
+    allcolors=codeblue
 }
 
 % Folders where to search for images