unshield (extractor for Microsoft InstallShield cabinet files)

Unshield extracts CAB files from InstallShield installers, used to
install software on Microsoft Windows based machines. The goals of
this implementation are:

- Use a well known open source license (MIT)
- Work on both little-endian and big-endian systems
- Separate the implementation into a tool and a library
- Support InstallShield versions 5 and later
- Be able to list contents of InstallShield Cabinet Files
- Be able to extract files from InstallShield Cabinet Files
