Increasing responsiveness

[aeph6Ee0]

This PR increases the responsiveness in two ways:

Skipping and Quitting

Currently if 'n' or 'q' command is submitted, it takes up to 30 seconds for the program to respond.

This issue is resolved by introducing a signaling mechanism (queue) to wake up the thread on those events, such that the thread can immediately respond to those events.

Quitting via Ctrl-c

Currently the program hangs when trying to kill it with Ctrl-c.

This issue is resolved by handling the KeyboardInterrupt exception and cleanly shutting down the program immediately.

[okraits]

Thank you for the pull request. I'm pretty busy at the moment but I will take a look at it when I have the time.

[okraits]

Regarding your first commit: I'm not so happy with using queues for that. I would rather use condition objects or event objects for this.

What do you think about this?

[aeph6Ee0]

I agree with you that for the current implementation, a condition or event object would be sufficient.
However, I already thought about further code improvements.
Currently the command variable is (unnecessarily) global, which is in general undesired. So I planned to send the command string via the queue to the thread directly in order to avoid the global scope. Queues are predestined for sending a variety of different events in a multithreaded environment.