LaTeX template: Respect numbersections for books (#5235)

Ensure that `\part` and `\chapter` are only numbered if `numbersections` is set. To return to the previous behaviour, use `-V numbersections -V secnumdepth=0`.

Notes on secnumdepth:

1 = Number `\section`
0 = Number `\chapter`
-1 = Number `\part`
-2 = No numbering

data/templates/default.latex

@@ -277,7 +277,7 @@ $endif$
 $if(numbersections)$
 \setcounter{secnumdepth}{$if(secnumdepth)$$secnumdepth$$else$5$endif$}
 $else$
-\setcounter{secnumdepth}{0}
+\setcounter{secnumdepth}{-2}
 $endif$
 $if(beamer)$
 $else$

test/lhs-test.latex

@@ -79,7 +79,7 @@
 \setlength{\emergencystretch}{3em}  % prevent overfull lines
 \providecommand{\tightlist}{%
   \setlength{\itemsep}{0pt}\setlength{\parskip}{0pt}}
-\setcounter{secnumdepth}{0}
+\setcounter{secnumdepth}{-2}
 % Redefines (sub)paragraphs to behave more like sections
 \ifx\paragraph\undefined\else
   \let\oldparagraph\paragraph

test/lhs-test.latex+lhs

@@ -44,7 +44,7 @@
 \setlength{\emergencystretch}{3em}  % prevent overfull lines
 \providecommand{\tightlist}{%
   \setlength{\itemsep}{0pt}\setlength{\parskip}{0pt}}
-\setcounter{secnumdepth}{0}
+\setcounter{secnumdepth}{-2}
 % Redefines (sub)paragraphs to behave more like sections
 \ifx\paragraph\undefined\else
   \let\oldparagraph\paragraph

test/writer.latex

@@ -57,7 +57,7 @@
 \setlength{\emergencystretch}{3em}  % prevent overfull lines
 \providecommand{\tightlist}{%
   \setlength{\itemsep}{0pt}\setlength{\parskip}{0pt}}
-\setcounter{secnumdepth}{0}
+\setcounter{secnumdepth}{-2}
 % Redefines (sub)paragraphs to behave more like sections
 \ifx\paragraph\undefined\else
   \let\oldparagraph\paragraph

test/writers-lang-and-dir.latex

@@ -42,7 +42,7 @@
 \setlength{\emergencystretch}{3em}  % prevent overfull lines
 \providecommand{\tightlist}{%
   \setlength{\itemsep}{0pt}\setlength{\parskip}{0pt}}
-\setcounter{secnumdepth}{0}
+\setcounter{secnumdepth}{-2}
 % Redefines (sub)paragraphs to behave more like sections
 \ifx\paragraph\undefined\else
   \let\oldparagraph\paragraph