Disable Alt and Meta by default

The Meta key is not useful.
The Alt key can be used in a terminal but is not useful to a part of
terminal users.

srcs/juloo.keyboard2/ExtraKeyCheckBoxPreference.java

@@ -40,9 +40,6 @@ public class ExtraKeyCheckBoxPreference extends CheckBoxPreference
   {
     switch (name)
     {
-      case "alt":
-      case "meta":
-        return true;
       default:
         return false;
     }