File::NFSLock - perl module to do NFS (or not) locking.

The module is based of concept of hard linking of files being atomic
across NFS. This concept was mentioned in Mail::Box::Locker (which was
originally presented in Mail::Folder::Maildir). Some routine flow is
taken from there -- particularly the idea of creating a random local
file, hard linking a common file to the local file, and then checking
the nlink status. Some ideologies were not complete (uncache mechanism,
shared locking) and some coding was even incorrect (wrong stat index).
File::NFSLock was written to be light, generic, and fast.
