- add "make build-pot" to build or update translations/tiramisu.pot files

- corrections in error's message in tiramisu/option.py
- update tiramisu.pot
- update fr's translation

Makefile

@@ -49,6 +49,10 @@ clean:
 #test: clean
 #	py.test
 
+# Build or update Portable Object Base Translation for gettext
+build-pot:
+	pygettext.py -p translations/ -o tiramisu.pot `find tiramisu/ -name "*.py"`
+
 build-lang:
 	$(call build_translation, $(TRADUC_DIR))
 
@@ -73,4 +77,4 @@ dist: version.in
 	  && tar --xform "s,\(.*\),$(PACKAGE)-$(VERSION)/\1," -f $(PACKAGE)-$(VERSION).tar -r version.in \
 	  && gzip -9 $(PACKAGE)-$(VERSION).tar
 
-.PHONY: all clean test install version.in dist
+.PHONY: all clean test install version.in dist build-pot