Fixed locale for identification of non-translated messages.

src/main/java/org/orekit/rugged/errors/RuggedMessages.java

@@ -116,7 +116,7 @@ public enum RuggedMessages implements Localizable {
                 final String translated = bundle.getString(name());
                 if ((translated != null) &&
                     (translated.length() > 0) &&
-                    (!translated.toLowerCase().contains("missing translation"))) {
+                    (!translated.toLowerCase(locale).contains("missing translation"))) {
                     // the value of the resource is the translated format
                     return translated;
                 }