Keep track of visited links

[makew0rld]

As emailed to me, referring to the subscription page specifically:

add the possibility to differentiate read and unread links, maybe by setting a specific color on read links ? I have dozens of updates a day so it can be a mess at the end of the day as it is :D

This would not be so hard to add for remembering which links were visited during the current browser session. Keeping track of visited links between sessions falls under a general history feature and is outside the scope of this issue.