Intial i18n messages support

Send different languages of messages based on player's client setting

src/main/java/fr/xephi/authme/util/PlayerUtils.java

@@ -1,7 +1,10 @@
 package fr.xephi.authme.util;
 
+import org.bukkit.command.CommandSender;
 import org.bukkit.entity.Player;
 
+import java.lang.reflect.Method;
+
 /**
  * Player utilities.
  */
@@ -36,4 +39,30 @@ public final class PlayerUtils {
         }
     }
 
+    /**
+     * Returns the locale that player uses.
+     *
+     * @param sender The player
+     */
+    public static String getLocale(CommandSender sender) {
+        String locale = null;
+
+        if (sender instanceof Player) {
+            Player player = (Player) sender;
+            if (Utils.majorVersion >= 12) {
+                locale = player.getLocale();
+            } else {
+                try {
+                    Method spigotMethod = player.getClass().getMethod("spigot");
+                    Object spigot = spigotMethod.invoke(player);
+
+                    Method spigotGetLocaleMethod = spigot.getClass().getMethod("getLocale");
+                    locale = (String) spigotGetLocaleMethod.invoke(spigot);
+                } catch (Exception ignored) {
+                }
+            }
+        }
+
+        return locale;
+    }
 }

src/main/java/fr/xephi/authme/util/Utils.java

@@ -2,6 +2,7 @@ package fr.xephi.authme.util;
 
 import fr.xephi.authme.ConsoleLogger;
 import fr.xephi.authme.output.ConsoleLoggerFactory;
+import org.bukkit.Bukkit;
 import org.bukkit.ChatColor;
 import org.bukkit.command.CommandSender;
 import org.bukkit.command.ConsoleCommandSender;
@@ -107,4 +108,12 @@ public final class Utils {
     public static boolean isEmailEmpty(String email) {
         return StringUtils.isBlank(email) || "your@email.com".equalsIgnoreCase(email);
     }
+
+    private final static String[] serverVersion = Bukkit.getServer().getBukkitVersion()
+        .substring(0, Bukkit.getServer().getBukkitVersion().indexOf("-"))
+        .split("\\.");
+
+    private final static int mcFirstVersion = Integer.parseInt(serverVersion[0]);
+    public final static int majorVersion = Integer.parseInt(serverVersion[1]);
+    public final static int minorVersion = Integer.parseInt(serverVersion[2]);
 }