Remove MANIFEST.in and related lint check

Because setuptools_scm already includes all version-controlled files
in an sdist, we don't need to maintain a MANIFEST.in file and anymore

See pytest-dev/pytest-xdist#161

MANIFEST.in

@@ -1,39 +0,0 @@
-include CHANGELOG.rst
-include LICENSE
-include AUTHORS
-include pyproject.toml
-
-include README.rst
-include CONTRIBUTING.rst
-include HOWTORELEASE.rst
-
-include tox.ini
-include setup.py
-
-recursive-include changelog *
-recursive-include scripts *.py
-recursive-include scripts *.bat
-
-include .coveragerc
-
-recursive-include bench *.py
-recursive-include extra *.py
-
-graft testing
-graft doc
-prune doc/en/_build
-graft tasks
-
-exclude _pytest/impl
-
-graft _pytest/vendored_packages
-
-recursive-exclude * *.pyc *.pyo
-recursive-exclude testing/.hypothesis *
-recursive-exclude testing/freeze/~ *
-recursive-exclude testing/freeze/build *
-recursive-exclude testing/freeze/dist *
-
-exclude appveyor.yml
-exclude .travis.yml
-prune .github

scripts/check-manifest.py

@@ -1,20 +0,0 @@
-"""
-Script used by tox.ini to check the manifest file if we are under version control, or skip the
-check altogether if not.
-
-"check-manifest" will needs a vcs to work, which is not available when testing the package
-instead of the source code (with ``devpi test`` for example).
-"""
-
-from __future__ import print_function
-
-import os
-import subprocess
-import sys
-from check_manifest import main
-
-if os.path.isdir('.git'):
-    sys.exit(main())
-else:
-    print('No .git directory found, skipping checking the manifest file')
-    sys.exit(0)

tox.ini

@@ -57,9 +57,7 @@ deps =
     # pygments required by rst-lint
     pygments  
     restructuredtext_lint
-    check-manifest
 commands =
-    {envpython} scripts/check-manifest.py
     flake8 pytest.py _pytest testing
     {envpython} scripts/check-rst.py