Crash problem

[lexiaoyao20]

SocketIOClient.swift

public func engineDidClose(reason: String) {
        waitingPackets.removeAll()

        if status != .disconnected {
            status = .notConnected
        }

        if status == .disconnected || !reconnects {
            didDisconnect(reason: reason)
        } else if !reconnecting {
            reconnecting = true
            tryReconnect(reason: reason)
        }
    }

SocketParsable.swift

func parseBinaryData(_ data: Data) {
        guard !waitingPackets.isEmpty else {
            DefaultSocketLogger.Logger.error("Got data when not remaking packet", type: "SocketParser")
            return
        }

        // Should execute event?
        guard waitingPackets[waitingPackets.count - 1].addData(data) else { return }

        let packet = waitingPackets.removeLast()

        if packet.type != .binaryAck {
            handleEvent(packet.event, data: packet.args, isInternalMessage: false, withAck: packet.id)
        } else {
            handleAck(packet.id, data: packet.args)
        }
    }

crash at this method let packet = waitingPackets.removeLast(), perhaps caused by multi-threaded，waitingPackets.removeAll() this method need to run in parseQueue.

[wenssh]

this pr cause a new crash, see /issues/562. Can you review this pr again? thanks.