brewkit.rb changes ENV destructively, so lets not do that everytime a formula
is required. Now it's possible for other tools to require a formula
description without worrying about side-effects.
A C library for encoding data in a QR Code symbol, a kind of 2D symbology
that can be scanned by handy terminals such as a mobile phone with CCD. The
capacity of QR Code is up to 7000 digits or 4000 characters, and is highly
robust.