OpenFOAM branching strategy

• Use a single repo.
  • Are commits even cherry-picked e.g. from dev into 3.0.x, or are they copy/pasted? Hashes are not the same.
• Stop patching old versions. These should be tags in the main repo. They could be branches, and commits from master could be cherry-picked.
• User dir could be simply called $USER-foam? Using a single repo would make it harder to use multiple versions simultaneously. Or would it? Users could name the repos whatever they wanted, and source the appropriate rc, but the $WM_PROJECT_USER_DIR may be ambiguous. It could go in $HOME/OpenFOAM/$USER-$(git describe) or something, but this would make things difficult if only changing commits in $WM_PROJECT_DIR, rather than hopping from tag to tag.