Add basic flake8 check

Partial solution to #181

.gitlab-ci.yml

@@ -38,6 +38,7 @@ python-3:
     - pip install -r optional_requirements.txt
     - pip install 'coverage>=4.5'
     - pip install coverage-badge
+    - pip install flake8
   script:
     - python setup.py install
     # Run tests and collect coverage data
@@ -66,6 +67,9 @@ python-3:
     - make clean
     - make html
 
+    # Run pyflakes
+    - flake8 .
+
   artifacts:
     paths:
       - htmlcov/

setup.cfg

+[flake8]
+exclude = .git,docs,build,dist
+max-line-length = 160