1) Introduced `--dry` option for `dvc repro` that only prints commands without actually executing;
2) Intrudced `-i|--interactive` option for `dvc repro` that reproduces stages in interactive mode, asking user for confirmation. Also introduced `core.interactive` option for the config to make it default behaviour;
3) Optimizations for remote dependencies/outputs;
4) Multiple UX improvements;
5) Bug fixes;