Repository layout: adopt a standard master branch with all supported versions

[jouvin]

For reasons I forgot, when we created this repo at SVN -> Git migration time, we opted for a branch per middleware version and no master branch. It turned out not to be a great idea: it makes everything more complicated, including:

• A release must tag several branches
• Fixing a problem affecting several middleware versions requires several PRs
• get-template-library must do complicated things to select all the branches to checkout
• Obsoleting a branch requires renaming it with a .obsolete suffix rather than removing the corresponding set of templates in the master branch

My proposal is to move to a standard structure with a master branch and have a first level directory representing the middleware version the templates must be used for, e.g. umd-4, umd-5 ... and to adapt the release tools and get-template-library to deal with this new/simpler structure.

Does anybody disagree? It should be transparent to template-library-grid users, in fact it should make their life easier. If there is an agreement, do you want to do it in the upcoming release, 24.10? Adding explicitely @jrha and @Pansanel .

Proposed plan includes:

• Create new main branch from umd-4 branch
• Adapt release tools to the new (simpler) layout
• Update the repository structure description in get-library-template

Ideally, should be done before adding umd-5 templates to simplify the operation and avoid the need to "merge" 2 branches with their history.

[jrha]

Duplicate of quattor/release#309 ?

[jrha]

We are definitely not doing it this (24.10) release though, it will break too many things in the release process.

[jouvin]

No I don't think it duplicates quattor/release#309 that I forgot and tend to disagree with... Ok, I'll try to make the change once 24.10 is released.

[jrha]

quattor/release#370