Functions for displaying, removing and saving.
- Display the part.
- Remove the part (if it has been displayed).
- Say whether a MIME type can be displayed inline.
- Say whether a MIME type should be displayed automatically.
- Free all resources occupied by a part.
- Offer to save the part in a file.
- Offer to pipe the part to some process.
- Prompt for a mailcap method to use to view the part.