Option for opening all files in new window

Hi

First thanks for the great plugin, I find it very useful however I had to make a little modification to add the ability to open all open files in a new window.

For me it was as simple as:

```
for view in self.window.views():
    sublime.windows()[-1:][0].open_file(view.file_name())
```

It would be nice to have this feature.

Thanks again...
