Implement CI also for macOS. Test merge requests on our macOS 10.13 test system.
The pipline now consists of two steps with three different jobs. First the compliance
with the code formating rules is checked. If this step succeed the code is build and
tested on Linux and macOS. This step runs simultaneous on both platforms.

Only run the piplines when there is a MR to the master branch.
Properly connect the official CbmRoot repository for the format checker
such that the differing source files can be found.
Add a shell script to do this.

Apply code formatting to all source/header files and root macros.

Add line which was removed by accident.

Administrator authored Jul 08, 2020 and Florian Uhlig committed Jul 09, 2020

Add format check in GitLab CI configuration file.
Add CMake target for format checker .
Add neede CMake files and shell scripts.
Add label in GitLab CI configuration file such that it can be
properly sorted on CDash.
The checker is disabled till we format the complete code base.

Pipeline now fails also in case of failing tests.
New CI option MergeRequest for Dart.sh wrapper which creates a special CDash label.
Use new CI option when GitLab CI runs for a merge request.

This version is an exact copy of the last revision of the trunk branch
of the old SVN repository of CbmRoor at
https://subversion.gsi.de/cbmsoft/cbmroot/trunk
The old SVN repository will still be available for read access.