Add a code-smell test for smart quotes and remove smart quotes from all files

test/sanity/code-smell/no-smart-quotes.sh

@@ -0,0 +1,23 @@
+#!/bin/sh
+
+# shellcheck disable=SC1015,SC1016
+egrep -r '[‘’“”]' . \
+    --exclude-dir .git \
+    --exclude-dir .tox \
+    | grep -v \
+    -e './test/sanity/code-smell/no-smart-quotes.sh' \
+    -e './docs/docsite/rst/dev_guide/testing/sanity/no-smart-quotes.rst' \
+    -e './test/integration/targets/unicode/unicode.yml' \
+    -e '\.doctree matches$' \
+    -e '\.pickle matches$' \
+    -e './docs/docsite/_build/html/'
+
+if [ $? -ne 1 ]; then
+    printf 'The file(s) listed above have non-ascii quotes.\n'
+    # shellcheck disable=SC1015,SC1016
+    printf 'Make sure all files use " and '"'"' as quotation marks\n'
+    printf 'These sed commands may be of help to you:\n'
+    # shellcheck disable=SC1015,SC1016
+    printf "  sed 's/[”“]/\"/g' \$FILENAME -i && sed \"s/[‘’]/'/g\" \$FILENAME -i\\n"
+    exit 1
+fi