do not show language dialog until there are some translations

gui/griffon-app/i18n/messages_bg.properties

@@ -1 +0,0 @@
-EXIT=Изход

gui/griffon-app/lifecycle/Initialize.groovy

@@ -205,6 +205,8 @@ class Initialize extends AbstractLifecycleHandler {
     }
 
     private String showLanguageDialog() {
+        if (Translator.SUPPORTED_LOCALES.size() == 1)
+            return Locale.US.toLanguageTag()
         def builder = new SwingBuilder()
         def languageComboBox
         def chooseButton

gui/src/main/java/com/muwire/gui/Translator.java

@@ -1,6 +1,5 @@
 package com.muwire.gui;
 
-import java.text.ChoiceFormat;
 import java.text.MessageFormat;
 import java.util.ArrayList;
 import java.util.LinkedHashSet;
@@ -16,7 +15,6 @@ public class Translator {
     public static final Set<Locale> SUPPORTED_LOCALES = new LinkedHashSet<>();
     static {
         SUPPORTED_LOCALES.add(Locale.US);
-        SUPPORTED_LOCALES.add(Locale.forLanguageTag("bg"));
         // add more as they get translated
     }