Proper settings views

[tulir]

The settings view needs to be redesigned and should be organized more sensibly. However, being able to change preferences per room/device must remain possible. The best design is probably some kind of toggle or tabbed view where you can choose which scope to modify, but only see the settings for one scope at a time.

The settings should also be organized into different categories, which should use more tabs (probably in a different orientation than scopes if those use tabs too) or just sections on the page.

There should be separate buttons to open global settings and room settings. Room settings should also include more room state things like changing name/avatar/topic, power levels and such