Changes by: Jason Hickey (jyh at cs.caltech.edu)
Date: 2004-06-13 19:57:43 -0700 (Sun, 13 Jun 2004)
Revision: 5897
Log message:
This is the new file model.
Differences:
1. Instead of "save ()", use "backup ()".
2. Instead of "export ()", use "save ()".
3. "backup_all ()" is called automatically when you exit.
4. If you really want to quit without saving, use "abort ()".
5. To revert to the last save, use "revert ()".
Just to be clear, *only* the files that you have modified
are backed-up when you quit.