调整卡牌攻击

- 场上存在卡牌时无法直接攻击敌方玩家
- 取消卡牌攻击敌方玩家高亮显示
- 一回合只能上场一张角色卡

Assets/TcgEngine/Scripts/GameClient/BoardSlotGroup.cs

@@ -77,8 +77,8 @@ namespace TcgEngine.Client
             {
                 foreach (GroupSlot slot in group_slots)
                 {
-                    if(gdata.CanPlayCard(dcard, slot.slot))
-                        target_alpha = 1f; //hightlight when dragging a character or artifact
+                    if(gdata.CanPlayCard(dcard, slot.slot, true))
+                        target_alpha = 1f; //hightlight when dragging a character or artifact (skip mana cost)
                 }
             }