Bitfinex: Fix websocket trade processing (#1754)

* Bitfinex: Fix WS trade processing

* Add handling for funding trades

Fixes #1746

* Linter: Disable shadow linting for err

It's been a year, and I'm still getting caught out by govet demanding I
don't shadow a var I was deliberately shadowing.
Made worse by an increase in clashes with stylecheck when they both want
opposite things on the same line.

* Bitfinex: Move websocket constants to websocket file

* Bitfinex: Rename channel consts

* Bitfinex: Send individual WS trades down the DataHandler

engine/websocketroutine_manager.go

@@ -242,9 +242,7 @@ func (m *WebsocketRoutineManager) websocketDataHandler(exchName string, data int
 			}
 			m.syncer.PrintTickerSummary(&d[x], "websocket", err)
 		}
-	case order.Detail,
-		ticker.Price,
-		orderbook.Depth:
+	case order.Detail, ticker.Price, orderbook.Depth:
 		return errUseAPointer
 	case stream.KlineData:
 		if m.verbose {
@@ -347,7 +345,7 @@ func (m *WebsocketRoutineManager) websocketDataHandler(exchName string, data int
 				m.printAccountHoldingsChangeSummary(d[x])
 			}
 		}
-	case []trade.Data:
+	case []trade.Data, trade.Data:
 		if m.verbose {
 			log.Infof(log.Trade, "%+v", d)
 		}