Minor UX improvements

[heapwolf]

• [ ] Remove the secondary bar and add Mute and Delete as popup options. The popup could spawned be a cog that is displayed at the right of the currently selected channel in the channel list.

• [ ] request invite and import feed could be modal dialogs spawned from the menu.

• [ ] Ability to toggle menu on and off in linux.

• [ ] Sidebar could be percentage based, but have a max-width.