Right Sidebars

[staab]

The best way to surface feed controls would be to use a right-hand sidebar, per #389. There is also a lot of wasted space in the app, and the main column is off-center. We should add sidebars to every page (or at least reserved space). This is a great opportunity to add context where it's needed, but also a ton of work.

• Decide whether such a large change is worth doing
• Design sidebars for relevant pages
• Add the sidebars to the code

[staab]

Closed in favor of #515