Project cleanup

[mondeja]

I've found this extension very helpful, so I've decided to update the project.

This pull does not include any code feature nor any bug fix in source code, so you can remain the same version. There are the changes listed:

• README.md:
  • TravisCI build badge links updated to point to this repository.
  • Title markup changed accordingly to Markdown format extension of the file.
• setup.py:
  • Requirements have been grouped by extras marks. You can install development extras in edit mode executing python -m pip install -e .[dev], for example.
  • Long description is now read from README.md to include badges in PyPI project page.
  • New classifier added for Python3.8.
  • The file requirements_dev.txt have been deleted to avoid redundance with setup.py.
  • sphinx_rtd_theme freezed to 0.4.3.
  • Linted using flake8 standard rules.
  • Along with this pull I suggest merge Add LICENSE to the manifest for PyPI #118 to ensure that distribution tarballs are correct.
• tox.ini:
  • Added all the Python versions supported by TravisCI, and a environment to test linting against flake8.
  • Configuration uses setup.py extras to install dependencies.
  • Flake8 ignores have been removed, and setup.py files along with sphinxarg/ and test/ folders are now explicitly linted.
• .travis.yml
  • Test against all Python versions supported using tox configuration.
• sphinxarg/:
  • Linted using flake8 standard rules.
• test/:
  • Linted using flake8 standard rules.
  • Replaced py.test expected hardcoded outputs by parser.prog to ensure that tests can be executed using pytest and py.test binaries. Closes Some tests fail when py.test has a different name #121
• docs/:
  • Fixed output error A random paragraph.
  • Copyright year from 2017 to now.
  • Users must use tox to test in contrib.rst.

You can see the TravisCI build success of this fork here.

I think that this should be enough for now. If this pull is merged, the project could be maintained with new features.

Anyway, thanks for your work. Greetings!