- now works as sub commands to git if copied to $(git --exec-path)
- now works with arbitrary commands for branch types
- consistent variable names
- new branch type 'support' for long-term support branches of historic
  versions
- preliminary base branch support for hotfix branch type to create
  hotfixes form support branches

Don't do --no-ff merges for feature branches that exist of a single commit (no benefits are gained in those situations, only complexity is added).

Functionally implemented the gitflow-feature subcommand. Starting and finishing feature branches is now possible in your repos.

Use a safer, more reliable way of determining what branches are available, by parsing the 'git branch' output instead of depending on files in the FS.

Add checks for all the commands, to assure we're working in a clean and safe environment, before actually modifying stuff in the repo.

Add function gitflow_require_branches_equal() to test whether local and remote branches have diverged.

- gitflow_require_local_branch()
- gitflow_require_remote_branch()
- gitflow_require_branch()