Introducing File::Symlink::Atomic

In Tips & tricks from my 4 months at Pythian, I showed how to give a symlink a new target atomically. I wasn’t aware of any module to encapsulate that, so I quickly put together File::Symlink::Atomic. This module is useful because it eliminates the need to know how to do this safely - simply use File::Symlink::Atomic and you get a drop-in replacement for CORE::symlink. It creates a temporary symlink (using File::Temp to get a unique pathname) pointing to your new target, then moves it into place with a rename call.