update WsOrderUpdate struct (#441)

[XanderShum]

add:

• TrailingDelta int64 json:"d"
• TrailingTime int64 json:"D"
• StrategyId int64 json:"j"
• StrategyType int64 json:"J"
• WorkingTime int64 json:"W"
• SelfTradePreventionMode string json:"V"

[0xkookoo]

I encountered this issue and finally find out why, then you fixed it already, much thanks!