use a mutex instead of a lock for more efficient/simple locking

[f1sherman]

I thought it might be easier to use a Mutex for the locking between the listener/interactor threads. Take a look and let me know what you think. Thanks for the awesome tool!

/Brian

[netzpirat]

This is an excellent use of a Mutex and makes everything much simpler. Thank you very much!

[thibaudgg]

Awesome, thanks!

[thibaudgg]

Sadly it seems to have an issue with the mutex way. Interactor should be locked more aggressively (like before) don't you think?

[f1sherman]

Good catch! I didn't anticipate that the interactor thread would continue to capture input from stdin, but it looks like that's what is happening. I'll be submitting another pull request for you momentarily.