refactor do_not_scale -> autoscale, code done, docs to be done

People (and I in particular) find expresions that look like
```python
if not director.do_not_scale_window:
```

a bit confusing.

I like to eliminate this implicit double negation by the refactor
 * replace  in director.init the kw-param 'do_not_scale'=False with 'autoscale'=True
 * replace in director the member 'do_not_scale_window' with the member 'autoscale', which will have the opposite semantic
 * adjust the  code to that change to get the same behavior.

@r1chardj0n3s  Do you have objections to that change ? Prefer another new name ? 

Docstrings updated, documentation still not adjusted, just in case.