Handle MARK properly for extensions.

Since you are asking that we use extensions for protocols, they need to be MARK’d correctly now for the drop-down thing that shows your file structure to work properly.  My suggestion is like so:

<!-- language: lang-swift -->

    class MyClass : UIViewController {
        // MARK: - Height related
        func heightFunc() {
             
        }
        
        // MARK: - Weight realted
        func weightFunc() {
            
        }
    }

    // MARK: - UITableViewDataSource -
    extension MyClass : UITableViewDataSource {
        func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        }
        
        func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        }
    }

That makes it looks like so:

![screen shot 2014-12-14 at 9 40 04 am](https://cloud.githubusercontent.com/assets/315966/5428356/3dcf6c7a-8375-11e4-9535-7d003ee29d79.png)