Add copy+paste ability to the properties

```
Add copy+paste ability to the properties:
1. Copy+paste of group, will duplicate the whole group with the new name.
2. Copy+paste of encoder, will duplicate the encoder with the new name.
The option may be added to the pop-up menu as "Duplicate".

```

Original issue reported on code.google.com by `tarlog` on 23 Nov 2008 at 9:37
