Update setup.md, add to navigation, remove whatsnew and vision

This is still a WIP. Do not merge.

//cc @zekiel @jkanarek 
Using a local text editor is okay, it would be the same as me writing my code in sublime-text and pasting it into Codio. That shouldn't cause any problems, but if they want to test locally it becomes an issue. I just don't want them to think "oh great, I have to use some crappy web-based text editor that isn't customized" because many devs have spent time customizing their editor.