Release checklist

DCCL Release Checklist:

• Merge all relevant pull requests into version branch (e.g. 3.0)
• Check build and unit tests
• Update version, release date (and soversion, if relevant) in CMakeLists.txt and in version.txt
• Commit
• Tag with version (e.g. git tag 3.0.10)
• Push with tags (git push && git push --tags)
• Click "Draft a new release" at https://github.com/GobySoft/dccl/releases