This is a Ruby module which provides file locking mechanism.
The module FileLock implements two classes: LockFile and LockedFile;
the class LockFile deals with so-called lockfiles, and the class
LockedFile offer a high-level interface to deal with both regular
files and lockfiles at the same time.
To be portable, a small C extension is used to minimize the time
between existence check of a lockfile and its creation.
