Fix lq/@href handling for HTML and PDF #1103

**[Gist](https://gist.github.com/eerohele/9476361)**.

Use the same handling logic for `lq/@href` as e.g. for `xref/@href`.

I left everything related to the `lq/@type` attribute as is for now because I wasn't sure whether we want to add any code for handling deprecated attributes.

Also, not sure whether adding unit test cases for `<lq>` is useful here since `<xref>` is already being tested, but let me know if you want me to add them.