Do not translate labels of boards submenus

Otherwise it may happen some weird sorting when untraslated and
translated labels are sorted together:

    Arduino megaAVR Boards
    Arduino nRF52 Board
    ESP32 Arduino
    ESP8266 Modules
    Schede Arduino AVR   <-- the localized string falls to the bottom

Also there is no way for 3rd party boards developers to actually provide
a translation, so let's just remove them.

Author: cmaglie

Diff for: app/src/processing/app/Base.java

@@ -1481,19 +1481,22 @@ public void actionPerformed(ActionEvent actionevent) {
     ButtonGroup boardsButtonGroup = new ButtonGroup();
     Map<String, ButtonGroup> buttonGroupsMap = new HashMap<>();
 
-    List<JMenu> platformMenus = new ArrayList<JMenu>();
+    class PlatformJMenu extends JMenu {
+      public PlatformJMenu(TargetPlatform pl) {
+        String text = pl.getPreferences().get("name");
+        if (text == null) {
+          text = pl.getContainerPackage().getId() + "-" + pl.getId();
+        }
+        setText(text);
+      }
+    }
+    List<PlatformJMenu> platformMenus = new ArrayList<>();
 
     // Cycle through all packages
     for (TargetPackage targetPackage : BaseNoGui.packages.values()) {
       // For every package cycle through all platform
       for (TargetPlatform targetPlatform : targetPackage.platforms()) {
-
-        // Add a title for each platform
-        String platformLabel = targetPlatform.getPreferences().get("name");
-        if (platformLabel == null)
-          platformLabel = targetPackage.getId() + "-" + targetPlatform.getId();
-
-        JMenu platformBoardsMenu = new JMenu(tr(platformLabel));
+        PlatformJMenu platformBoardsMenu = new PlatformJMenu(targetPlatform);
         MenuScroller.setScrollerFor(platformBoardsMenu);
         platformMenus.add(platformBoardsMenu);
 

Diff for: arduino-core/src/processing/app/I18n.java

@@ -106,10 +106,6 @@ public static String format(String fmt, Object... args) {
    * This method is an hack to extract words with gettext tool.
    */
   protected static void unusedStrings() {
-    // These phrases are defined in the "platform.txt".
-    tr("Arduino AVR Boards");
-    tr("Arduino ARM (32-bits) Boards");
-
     // This word is defined in the "boards.txt".
     tr("Processor");
   }