Version bump to 0.4.5
Use the most recent displayed comment instead of current time

Scenario:

 Load page at 10AM, don't read
 Leave open until 11AM
 Read comments at 11AM
 Click Mark Read at 11AM
 Refresh page

The comments from 10AM - 11AM are now marked as read, even though you
didn't read them.

The change fixes that by selecting the most recent displayed comment.

"Reset read data" keeps the old behavior.