Updated link underlining preference

The extra accessibility preference is removed, in favor of a more precise Link underlining preference. The link underlining can be set to three values:

• Yes: all links are underlined
• Only inline links: Only links in text blocks are underlined. This is the new default value. This is a compromise that allows to easily spot links in blocks of text without highlighting them in places where they are easy to see.
• No: No links are underlined. This is equivalent to the previous default value.

Note that on hover, links are always underlined, independently of the underline setting.

The screenshots display a page with the different preferences selected, in the same order as the one described above.