Icemac.install.addressbook

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- Change license from ZPL to MIT.

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- Also release as wheel.

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- `install-addressbook` now prints a message before starting the download.

- `archive-addressbook` now prints a message before starting archiving.

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- Prevent an error in `archive-addressbook` if the ``bz2`` module is not
available.

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- Add ``make-current-addressbook`` script to ease usage of the `current`
symlink in case of an error.

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- Initial release.