Add vendor (steam)

vendor/github.com/Philipp15b/go-steam/trade/doc.go

@@ -0,0 +1,40 @@
+/*
+Allows automation of Steam Trading.
+
+Usage
+
+Like go-steam, this package is event-based. Call Poll() until the trade has ended, that is until the TradeEndedEvent is emitted.
+
+	// After receiving the steam.TradeSessionStartEvent
+	t := trade.New(sessionIdCookie, steamLoginCookie, steamLoginSecure, event.Other)
+	for {
+		eventList, err := t.Poll()
+		if err != nil {
+			// error handling here
+			continue
+		}
+		for _, event := range eventList {
+			switch e := event.(type) {
+				case *trade.ChatEvent:
+					// respond to any chat message
+					t.Chat("Trading is awesome!")
+				case *trade.TradeEndedEvent:
+					return
+				// other event handlers here
+			}
+		}
+	}
+
+You can either log into steamcommunity.com and use the values of the `sessionId` and `steamLogin` cookies,
+or use go-steam and after logging in with client.Web.LogOn() and receiving the WebLoggedOnEvent use the `SessionId`
+and `SteamLogin` fields of steam.Web for the respective cookies.
+
+It is important that there is no delay between the Poll() calls greater than the timeout of the Steam client
+(currently five seconds before the trade partner sees a warning) or the trade will be closed automatically by Steam.
+
+Notes
+
+All method calls to Steam APIs are blocking. This packages' and its subpackages' types are not thread-safe and no calls to any method of the same
+trade instance may be done concurrently except when otherwise noted.
+*/
+package trade