Merge branch 'master' into python3-ci

* master: (28 commits)
  Update README to combine environment sections
  Update README
  os.path.samefile is not available on windows.
  Add shell-style execution on the Mac
  Use os.path.samefile to get around filename case insensitivity
  Add test for before_build executing in a shell
  Fix some linter warnings
  Add CIBW_ENVIRONMENT to README and reorder options
  Fix empty env string case
  Fix string splitting for the env string
  Making call from run_tests to run_test subprocess.check_call
  Fixing 'ValueError: Attempted relative import in non-package'
  Update README.md
  Reducing code duplication in bin/run_test.py and bin/run_tests.py
  Semicolons need quoting
  Ignore vscode project settings
  Windows uses a different pathsep so have to use that in the test
  Make shell evals work and add tests for that
  Use parse_environment in the main code
  Run the unit tests in CI
  ...

# Conflicts:
#	.travis.yml
#	appveyor.yml
#	run_tests.py

.travis.yml

@@ -24,10 +24,10 @@ matrix:
 script:
   - |
     if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then
-      $PYTHON -m pip install .
-      $PYTHON ./run_tests.py
+      $PYTHON -m pip install -r requirements-dev.txt
+      $PYTHON ./bin/run_tests.py
     else
       # linux test requires root to clean up the wheelhouse (docker runs as root)
-      sudo $PYTHON -m pip install .
-      sudo $PYTHON ./run_tests.py
+      sudo $PYTHON -m pip install -r requirements-dev.txt
+      sudo $PYTHON ./bin/run_tests.py
     fi