Library hangs on shutdown

[cdjackson]

It seems that the library often (nearly always?) hangs on closing at the following point -:

    /**
     * Requests parser thread to shutdown.
     */
    public void close() {
        this.close = true;
        try {
            parserThread.interrupt();
            parserThread.join();
        } catch (InterruptedException e) {
            logger.warn("Interrupted in packet parser thread shutdown join.");
        }
    }

Presumably the parserThread doesn't quit and it locks at the join.

[tlaukkan]

This is duplicate to #91