Language-tags

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- Bug fix release: language tag 'aa' is detected as invalid 27

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- Upgrade to <https://github.com/mattcg/language-subtag-registry/releases/tag/v0.3.18>

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- Official python 3.5 compatibility
- Upgrade to <https://github.com/mattcg/language-subtag-registry/releases/tag/v0.3.15>

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- Included the data folder again in the project package.
- Added bash script (`update_data_files.sh`) to download the
`language-subtag-registry <https://github.com/mattcg/language-subtag-registry/>`_
and move this data in the data folder of the project.

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- Allow parsing a redundant tag into subtags.
- Added package.json file for easy update of the language subtag registry data using `npm <https://docs.npmjs.com/>`_
(:code:`npm install` or :code:`npm update`)
- Improvement of the :code:`language-tags.tags.search` function: rank equal description at top.
See `mattcg/language-tags4 <https://github.com/mattcg/language-tags/issues/4>`_

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- Upgrade to <https://github.com/mattcg/language-subtag-registry/releases/tag/v0.3.11>
- Added wheel config
- Fixed bug under windows: opening data files using utf-8 encoding.