Put the extensions in a new git repository. Use the git repository as a submodule

Move ATLAS-Extensions from GeoModel Proper into a submodule, now called ATLASExtensions (without the hyphen). This is part of Marilena's refactoring proposal.

added 4 commits

• cf6d940a...4235b999 - 2 commits from branch master
• 6c27a724 - Put the extensions in a new git repository. Use the git repository as a submodule
• c75484b1 - Merge branch 'extensions-in-submodule' of...

Compare with previous version

enabled an automatic merge when the pipeline for c75484b1 succeeds

merged

mentioned in commit ca6884e1