`sidebar` style component

[injust]

I propose a sidebar style component, which should be equivalent to changes,numbers.

I like the full style, but wanted to remove the left sidebar for easy copying. I first removed numbers, then realized that changes also adds the left sidebar, so I had to remove that too.

--style=full,-sidebar reads much clearer than --style=full,-changes,-numbers, since it reflects what I want instead of what I did to achieve it.