Dflit

-----------

- Fixes for packages specifying ``requires-extra``: sdists should now work, and
environment markers can be used together with ``requires-extra``.
- Fix running ``flit installfrom`` without a config file present in the
working directory.
- The error message for a missing or empty docstring tells you what file
the docstring should be in.
- Improvements to documentation on version selectors for requirements.

-----------

- Packages can now have 'extras', specified as ``requires-extra`` in the
:doc:`pyproject.toml file <pyproject_toml>`. These are additional dependencies
for optional features.
- The ``home-page`` metadata field is no longer required.
- Additional project URLs are now validated.
- ``flit -V`` is now equivalent to ``flit --version``.
- Various improvements to documentation.

-----------

- The description file may now be written in reStructuredText, Markdown or
plain text. The file extension should indicate which of these formats it is
(``.rst``, ``.md`` or ``.txt``). Previously, only reStructuredText was
officially supported.
- Multiple links (e.g. documentation, bug tracker) can now be specified in a
new :ref:`[tool.flit.metadata.urls] section <pyproject_toml_urls>` of
``pyproject.toml``.
- Dependencies are now correctly installed to the target Python when you use
the ``--symlink`` or ``--pth-file`` options.
- Dependencies are only installed to the Python where Flit is running if
it fails to get the docstring and version number without them.
- The commands deprecated in 0.13—``flit wheel``, ``flit sdist`` and
``flit register``—have been removed.

Although version 1.0 sounds like a milestone, there's nothing that makes this
release especially significant. It doesn't represent a step change in stability
or completeness. Flit has been gradually maturing for some time, and I chose
this point to end the series of 0.x version numbers.

------------

- Better validation of several metadata fields (``dist-name``, ``requires``,
``requires-python``, ``home-page``), and of the version number.
- New :envvar:`FLIT_ALLOW_INVALID` environment variable to ignore validation
failures in case they go wrong.
- The list of valid classifiers is now fetched from Warehouse (https://pypi.org),
rather than the older https://pypi.python.org site.
- Deprecated ``flit wheel`` and ``flit sdist`` subcommands: use
:ref:`build_cmd`.
- Deprecated ``flit register``: you can no longer register a package separately
from uploading it.

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- Fix building and installing packages with a ``-`` in the distribution name.
- Fix numbering in README.

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- New tool to convert ``flit.ini`` to ``pyproject.toml``::

python3 -m flit.tomlify

- Use the PAX tar format for sdists, as specified by PEP 517.