[bin][runselected] ensure junit report is created

See merge request !2582

[ci] advise openmpi to run as root

See merge request !2581

[cmake] Avoid disallowed escape sequence (fixes cmake 3.16)

Closes #1022

See merge request !2580

[cleanup] Correct some typos and remove trailing white space

See merge request !2579

[ci] ensure pipeline creation in schedules

See merge request !2578

always run test-selection stage

See merge request !2576

Update README.md

See merge request !2577

This way, the pipeline result on master will always be the one of the 
last nightly scheduled pipeline.

the ci seems to sometimes fail to pass the created .yml file to the
subsequent stage. Thus, we now always run the test-selection stage but
skip script execution in case we are not in a merge request

The test selection script requires gcc to be used

[ci] manual trigger pipeline only when not scheduled

See merge request !2575

WIP Feature/ci integration

See merge request !2408

For a large number of tests, the resulting .yml could not be interpreted 
by the GitLab ci

use the generator script from the template instead