Sphinx-needs

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* Improvement: Introduction of needs :ref:`layouts_styles`.
* Improvement: Added config options :ref:`needs_layouts` and :ref:`needs_default_layout`.
* Improvement: Added :ref:`needpie` which draws pie-charts based on :ref:`filter_string`.
* Improvement: Added config option :ref:`needs_warnings`. (:issue:`110`)
* Bugfix: Need css style name is now based on need-type and not on the longer, whitespace-containing type name.
Example: ``need-test`` instead of not valid ``need-test case``. (:issue:`108`)
* Bugfix: No more exception raise if ``copy`` value not set inside :ref:`needs_extra_links`.
* Improvement: Better log message, if required id is missing. (:issue:`112`)

* Removed: Configuration option :ref:`needs_collapse_details`. This is now realized by :ref:`layouts`.
* Removed: Configuration option :ref:`needs_hide_options`. This is now realized by :ref:`layouts`.
* Removed: Need option :ref:`need_hide_status`. This is now realized by :ref:`layouts`.
* Removed: Need option :ref:`need_hide_tags`. This is now realized by :ref:`layouts`.

**WARNING**: This version changes a lot the html output and therefore the needed css selectors. So if you are using
custom css definitions you need to update them.

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* Improvement: Role :ref:`role_need` supports standard sphinx-ref syntax. Example: ``:need:`custom name <need_id>
* Improvement: Added :ref:`global_option_filters` to set values of global options only under custom circumstances.
* Improvement: Added sorting to :ref:`needtable`. See :ref:`needtable_sort` for details.
* Improvement: Added dynamic function :ref:`links_content` to calculated links to other needs automatically from need-content.
(:issue:`98`)
* Improvement: Dynamic function :ref:`copy` supports uppercase and lowercase transformation.
* Improvement: Dynamic function :ref:`copy` supports filter_string.
* Bugfix: Fixed corrupted :ref:`dynamic_functions` handling for ``tags`` and other list options.
(:issue:`100`)
* Bugfix: Double entries for same need in :ref:`needtable` fixed. (:issue:`93`)

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* Improvement: Added ``signature`` information to need-object. Usable inside :ref:`filter_string`.
Mainly needed by `Sphinx-Test-Reports <https://sphinx-test-reports.readthedocs.io/en/latest/>`_ to link imported
test cases to needs documented by
`sphinx-autodoc <https://www.sphinx-doc.org/en/master/usage/extensions/autodoc.html>`_.

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* Improvement: Added :ref:`need_style` option to allow custom styles for needs.
* Improvement: Added :ref:`needtable_style_row` option to allow custom styles for table rows and columns.

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* Improvement: Provides API for other sphinx-extensions. See :ref:`api` for documentation.
* Improvement: Added :ref:`support` page.
* Bugfix: Fixed deprecation warnings to support upcoming Sphinx3.0 API.

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* Improvement: In filter operations, all needs can be accessed by using keyword ``needs``.
* Bugfix: Removed prefix from normal needs for needtable (:issue:`97`)