cleanup: use semaphores for bordeaux-threads

[dkochmanski]

Previously BT didn't have semaphores implementation – it does now. Last year we've removed dependency on bt-semaphore in favour of hand-crafted CV-based solution. We should revert part of this pull request: #18 and use semaphore interface from BT now (file watcher.lisp).

This task does not require deep understanding of log4cl internals whatsoever and may be solved by beginners to get involved into the project.

[chuchana]

I guess this can be closed now? (#28)

[dkochmanski]

yes, thank you for bumping this thread. closing.