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.
FAAC is an Advanced Audio Coder (MPEG2-AAC, MPEG4-AAC). The goal of
FAAC is to explore the possibilities of AAC and exceed the quality
of the currently best MP3 encoders.
