add intllib support (i18n)

-> mods ontime_clocks, signs, signs_roads & steles

add french translations
add updatepo.sh script to update po/pot files
add specific array for full description of steles

signs_road/tools/updatepo.sh

@@ -0,0 +1,25 @@
+#! /bin/bash
+
+# To create a new translation:
+#   msginit --locale=ll_CC -o locale/ll_CC.po -i locale/template.pot
+
+cd "$(dirname "${BASH_SOURCE[0]}")/..";
+
+# Extract translatable strings.
+xgettext --from-code=UTF-8 \
+		--language=Lua \
+		--sort-by-file \
+		--keyword=S \
+		--keyword=NS:1,2 \
+		--keyword=N_ \
+		--keyword=F \
+		--add-comments='Translators:' \
+		--add-location=file \
+		-o locale/template.pot \
+		$(find . -name '*.lua')
+
+# Update translations.
+find locale -name '*.po' | while read -r file; do
+	echo $file
+	msgmerge --update $file locale/template.pot;
+done