There is no reason that people should have to connect to donationcoder.com using https, but doing so in the past could lead to browser warnings about pages being "partially secure" or other ridiculous warnings because some of the images on the page weren't using https protocol.
I spent a few hours this morning trying to improve that, so that most of the pages on DC and the forum should now load cleanly using https and use https on all links.
I think the forum should also now convert all links in posts that go to dc site pages, to https or http based on how you are currently connected, regardless of the original way a link was posted.