Removed The "Similar Topics" Popover

I’ve added some custom CSS to the site to hide the popover which appears over the preview window when you make a new topic suggesting that the new topic may be similar to other topics already in existence. I’ve never found that particularly helpful.

Let me know if I’ve caused any weird display bugs or if you particularly liked that feature.

The popover might come in handy waaaay down the line, but for now it isn’t really helpful.