Refine PR #730

Squashed commit of the following:

commit 48eb4d88391b85986190ace825ec0a167df16f8a
Author: Syrone Wong <wong.syrone@gmail.com>
Date:   Sun Sep 18 15:46:09 2016 +0800

    Drop useless interface impl

    Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

commit c0a4f3421a
Author: Logan Zhou <xorcererzc@gmail.com>
Date:   Sun Sep 18 00:58:02 2016 +0800

    Revert "Updated to meet the hint from Wongsyrone."

    This reverts commit 84c8053577.

commit 84c8053577
Author: Logan Zhou <xorcererzc@gmail.com>
Date:   Sun Sep 18 00:52:21 2016 +0800

    Updated to meet the hint from Wongsyrone.

commit 333ccb6d1f
Author: Logan Zhou <xorcererzc@gmail.com>
Date:   Sun Sep 18 00:34:52 2016 +0800

    Added duplicate button to config form.

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

shadowsocks-csharp/Data/cn.txt

@@ -39,6 +39,7 @@ Choose by statistics=根据统计
 
 &Add=添加(&A)
 &Delete=删除(&D)
+Dupli&cate=复制(&C)
 Server=服务器
 Server Addr=服务器地址
 Server Port=服务器端口

shadowsocks-csharp/Data/zh_tw.txt

@@ -39,6 +39,7 @@ Choose by statistics=根據統計
 
 &Add=新增(&A)
 &Delete=移除(&D)
+Dupli&cate=複製(&C)
 Server=伺服器
 Server Addr=伺服器位址
 Server Port=伺服器連接埠