Avoid line break between html elements and text

Considering the following example:

```

some long text… (example) …some long text… « example2 » some long text… example3.

```

Firefox, Safari, Chrome will never break between the texts in spans and the (immediate-)surrounding characters.

But, depending on the position of the text, openhtmltopdf may put a line break between:
- "(" and "example" or "example" and ")"
- same between "«"/"»" and "example2"
- same between example3 and "."

This results in not properly formatted text.
The texts here in the spans should be considered as being on the same level as the surrounding text.

More generally, this should probably be the default behavior for any inline tags.