FUSE img3 filesystem
read/write/encryption support

Usage example:

mkdir /tmp/img3
img3fs /tmp/img3 038-0032-002.dmg -iv 9b20ae16bebf4cf1b9101374c3ab0095 -key 06849aead2e9a6ca8a82c3929bad5c2368942e3681a3d5751720d2aacf0694c0
hdiutil attach /tmp/img3/DATA.dmg
rm -rf /Volumes/ramdisk/usr/local/standalone/firmware/*
echo "Hello World!" > /Volumes/ramdisk/hello.txt
hdiutil eject /Volumes/ramdisk
umount /tmp/img3