Introduce default assignment simplifications

There are many simplifications in pystencils that are usually not applied. They can be applied now by using a simple argument in the configuration.

Fixes #39 (closed)

.gitlab-ci.yml

@@ -142,17 +142,13 @@ ubuntu:
     - sed -i 's/--doctest-modules //g' pytest.ini
     - env
     - pip3 list
-    - pytest-3 -v -n $NUM_CORES --cov-report html --cov-report term --cov=. --junitxml=report.xml pystencils_tests/test_*vec*.py pystencils_tests/test_random.py
-    - python3 -m coverage xml
+    - pytest-3 -v -n $NUM_CORES --junitxml=report.xml pystencils_tests/test_*vec*.py pystencils_tests/test_random.py
   tags:
     - docker
     - AVX
   artifacts:
     when: always
-    paths:
-      - coverage_report
     reports:
-      cobertura: coverage.xml
       junit: report.xml
 
 arm64v8: