Export basic LaTeX file, too

According to manubot/rootstock#384

For kicks, we *also* set BUILD_DOCX, so we should also get a Word
file...

build/build.sh

@@ -10,6 +10,9 @@ set -o errexit \
 export TZ=Etc/UTC
 # Default Python to read/write text files using UTF-8 encoding
 export LC_ALL=en_US.UTF-8
+# Build both .tex and .doc file, too
+export BUILD_LATEX=true
+export BUILD_DOCX=true
 
 # Generate reference information
 echo >&2 "Retrieving and processing reference metadata"
@@ -85,6 +88,15 @@ if [ "${BUILD_DOCX:-}" = "true" ]; then
     --defaults=docx.yaml
 fi
 
+# Create LaTeX output (if BUILD_LATEX environment variable equals "true")
+if [ "${BUILD_LATEX:-}" = "true" ]; then
+  echo >&2 "Exporting LaTeX manuscript"
+  pandoc \
+      --data-dir="$PANDOC_DATA_DIR" \
+      --defaults=common.yaml \
+      --defaults=latex.yaml
+fi
+
 # Spellcheck
 if [ "${SPELLCHECK:-}" = "true" ]; then
   export ASPELL_CONF="add-extra-dicts $(pwd)/build/assets/custom-dictionary.txt; ignore-case true"

build/pandoc/defaults/latex.yaml

@@ -0,0 +1,4 @@
+# Pandoc --defaults for LaTeX output.
+# Load on top of common defaults.
+to: latex
+output-file: output/manuscript.tex