Remove obsolete IE6sux and IEsux comments from templates.

Remove `<!--IE6sux-->` comments.

Do enough users use IE6 to send these bytes to every user?
I use the latest version of Chrome, and when I visit the home page, this comment is sent about 70 times.
That means 910 bytes are sent, just to show this comment.
At the time of writing, last month, ~~this comment was~~ these comments were responsible for 4535.956 GB of data sent to users. That is, over 4 TB in a month. All for a comment to say IE6 sucks.

Since Reddit is aiming to become a profitable entity, I would recommend getting rid of this comment, and forcing IE6 users to upgrade. It will be about time.