exchanges/ftx: Order improvements: submission + websocket reports (#741)

* exchanges/ftx: add support for ReduceOnly, ImmediateOrCancel and PostOnly orders

* exchanges/ftx: adapt tests to ReduceOnly/ImmediateOrCancel/PostOnly boolean flags

* exchanges/ftx: wrong json key of WsFillsDataStore.FillsData was causing json.Unmarshal() to yield an empty struct

* exchanges/ftx: update WsFills to latest API

* exchanges/ftx: add TestFTX_wsHandleData_wsFills

* exchanges/ftx: WsOrders.FilledSize was never parsed properly because of a key error (was spelled `filedSize` -- with one L);  enrich data structure to support latest API fields

* exchanges/ftx: when order is closed, set status to closed, not canceled

* exchanges/ftx: compatibleOrderVars: compare floats for almost-equality

* order.Detail: add field: AverageExecutedPrice float64

* exchanges/ftx: FTX.wsHandleData() now populates all order.Detail fields properly on update/orders websocket message

* exchanges/ftx: implement TestFTX_wsHandleData_Details()

* exchanges/ftx: make golangci-lint happy

* exchanges/ftx: make golangci-lint happy

* exchanges/ftx/test: delete redundant commented code

* exchanges/ftx: move websocket tests from ftx_test.go to ftx_websocket_test.go

* exchanges/ftx: remove redundant line

* exchange/ftx: greatly simplify TestFTX_wsHandleData (thanks to @shazbert)

* exchanges/ftx: make golangci-lint/whitespace happy

* exchanges/ftx: requested review change: delete a redundant line

* exchanges/ftx/test: use predefined currency constants

exchanges/order/order_types.go

@@ -118,37 +118,38 @@ type ModifyResponse struct {
 // Each exchange has their own requirements, so not all fields
 // are required to be populated
 type Detail struct {
-	ImmediateOrCancel bool
-	HiddenOrder       bool
-	FillOrKill        bool
-	PostOnly          bool
-	Leverage          float64
-	Price             float64
-	Amount            float64
-	LimitPriceUpper   float64
-	LimitPriceLower   float64
-	TriggerPrice      float64
-	TargetAmount      float64
-	ExecutedAmount    float64
-	RemainingAmount   float64
-	Cost              float64
-	Fee               float64
-	Exchange          string
-	InternalOrderID   string
-	ID                string
-	ClientOrderID     string
-	AccountID         string
-	ClientID          string
-	WalletAddress     string
-	Type              Type
-	Side              Side
-	Status            Status
-	AssetType         asset.Item
-	Date              time.Time
-	CloseTime         time.Time
-	LastUpdated       time.Time
-	Pair              currency.Pair
-	Trades            []TradeHistory
+	ImmediateOrCancel    bool
+	HiddenOrder          bool
+	FillOrKill           bool
+	PostOnly             bool
+	Leverage             float64
+	Price                float64
+	Amount               float64
+	LimitPriceUpper      float64
+	LimitPriceLower      float64
+	TriggerPrice         float64
+	AverageExecutedPrice float64
+	TargetAmount         float64
+	ExecutedAmount       float64
+	RemainingAmount      float64
+	Cost                 float64
+	Fee                  float64
+	Exchange             string
+	InternalOrderID      string
+	ID                   string
+	ClientOrderID        string
+	AccountID            string
+	ClientID             string
+	WalletAddress        string
+	Type                 Type
+	Side                 Side
+	Status               Status
+	AssetType            asset.Item
+	Date                 time.Time
+	CloseTime            time.Time
+	LastUpdated          time.Time
+	Pair                 currency.Pair
+	Trades               []TradeHistory
 }
 
 // Filter contains all properties an order can be filtered for