Commoncode

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- Minor improved utilities
- More robust handling of Codebase with a single Resource

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- Remove usage of deprecated ``click.get_terminal_size()``.

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- Add ``warning`` field to ``commoncode.Codebase`` headers.
- Add new functions ``get_jar_nv()`` and ``get_nupkg_nv()`` that accepts
a filename of a JAR or nupkg and return a name/version tuple extracted
using multiple heuristics.

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- Switch back from calver to semver.
- Adopt latest skeleton. The default virtualenv directory is now venv and no
longer tmp
- Fix issue with Click progressbar API 23 that prohibited to use all supported
Click versions. Since Click is widely used that was a frequent source of
installation conflicts.

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- Add an attribute to the header for scancode output format versioning.
This is for https://github.com/nexB/scancode-toolkit/issues/2653

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- Ensure that the progressbar displays a counter correctly.
This is a fix for https://github.com/nexB/scancode-toolkit/issues/2583