User-visible changes:
- make 'got rebase' switch the work tree if no commits need rebasing
- let gotadmin find the repository automatically if invoked in a work tree
- preserve binary files during updates and merges instead of leaving them empty
- allow sorting references by timestamp in tog ref view
- add got ref -t option to sort listed references by modification time
- add got branch -t option to sort listed branches by modification time
c93ff21598