We aren't translating these settings, so it makes more sense to move them into the code. I added an instance method so plugins can add mappings for custom reasons.
We relied on backticks to identify and replace site setting names with links. Unfortunately, some translations don't follow this convention, breaking this feature.
Additionally, this lets us linkify `category settings` and `watched words` without using HTML in the translations.
You may notice that I split the texts we want to linkify into two groups. I did this on purpose to emphasize those that should be translated (regular_links) from those who don't (site_settings_link). If you can think of a better solution, I'm open to suggestions.