Include clang-format checking in gitlab-ci

We probably should not run clang-format directly, but we should run it as part of the unit tests to make sure the code is compliant.

mentioned in issue #156 (closed)

I agree. I'm considering to provide a helper script in the clang container(s) to make it easy to run the conformity checks locally. Or provide a top-level check-clang-format.sh script in the code.

But don't overlook the do-clang-format.sh script....

Sure, I was planning to use that as a starting point.

mentioned in merge request !123 (merged)

assigned to @rulrich

added Feature request label

mentioned in merge request !125 (merged)

closed via merge request !123 (merged)