Better error-messages for trades

Improved error messages for trades.  Also added an experimental fix for https://github.com/Jessecar96/SteamBot/issues/598
This isn't right IMHO. 3-5 should be handled together, and anything else should be retried.

    case TradeStatusType.TradeCancelled:
    case TradeStatusType.SessionExpired:
    case TradeStatusType.TradeFailed:
        // Handle the same.
    default:
        // Re-try.