Yet not implemented:

- Write blackbox tests for 'heads' command
- 'heads' command could use LOCATION argument for remote operations
- Implement various sorting schemes (by nick) -- req. Wouter van Heyst
- Resurrect heads without live branches - req. Eric Bagfors


Implemented:

- Implement various sorting schemes (by date [IMPLEMENTED]) -- req. Wouter van Heyst
- Show only heads without live branches [IMPLEMENTED] - req. Aaron Bentley
- Show tips of all live branches [IMPLEMENTED]
