L18n

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- add Python 3.10 support
- drop Python 2.7 support

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- fix pytz version number

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- fix maker encoding messages
- suppress python 3.7+ deprecated imports messages

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- fix installation bug on non-UTF8 platforms
- fix CLDR database archive download bug

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- Chinese (zh) translation overrides by Charlotte Blanc
- copy/deepcopy support for l18n lazy strings and dictionaries
- fix charset bug on python 2

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- items are now sorted in maps iterators
- subsets support