add_list somelist "A string with $var" causes the $var to be eval'ed

It should be possible to add a string to a list without having the string evaluated.

There may be _some_ use cases where the string should be eval'ed, but the default should be "as-is".

If someone really wants the string to be eval'ed before adding, just do this:

```
add_list somelist `eval "some string with $var"`
```
