add "add double faced card" menu option

data/ch-s.mse-locale/locale

@@ -54,6 +54,8 @@ menu:
 	next card:							选择下一张卡牌	PgDn
 	search cards:						搜索卡	Ctrl+K
 	add card:							添加卡牌	Ctrl+Enter
+	#TODO: Localize
+	add card double:					&Add Double Faced Card	Ctrl+Shift+Enter
 	add cards:							批量添加卡牌...
 	remove card:						删除所选卡牌
 	#TODO: Localize
@@ -208,6 +210,8 @@ help:
 	next card:							选择列表中的下一张卡牌
 	search cards:						使用搜索词过滤卡片列表
 	add card:							添加一个新的空白卡牌到本套牌
+	#TODO: Localize
+	add card double:					Add a new, blank, card that has a back face to this set
 	add cards:							添加多张卡牌到本套牌
 	remove card:						从本套牌中删除所选卡牌
 	#TODO: Localize
@@ -468,6 +472,8 @@ tooltip:
 
 	# cards toolbar
 	add card:							添加卡牌
+	#TODO: Localize
+	add card double:					Add double faced card
 	remove card:						移除选中卡牌
 	#TODO: Localize
 	link card:							Link cards to selected card