Chat table layout (but using flex boxes now, not ``display: table``)

This ought to fix the issues with chat-box sizing, using flex boxes.  I've not tested it in IE but it's solid in Chrome and Firefox.  IE11 at least ought to support this if nib expanded its syntax correctly, but we should definitely test that.

This PR also includes updates to the latest master (including the now merged admin/about refactors from @srish) which you'll need before merging.