Merge branch 'threecolumn' into 'develop'

src/App.js

src/App.scss

src/App.vue

src/boot/after_store.js

src/components/about/about.vue

src/components/account_actions/account_actions.vue

src/components/attachment/attachment.scss

src/components/chat/chat.js

src/components/chat/chat.scss

src/components/chat/chat.vue

src/components/chat/chat_layout_utils.js

src/components/chat_list/chat_list.vue

src/components/chat_list_item/chat_list_item.scss

src/components/chat_new/chat_new.scss

src/components/chat_new/chat_new.vue

src/components/chat_title/chat_title.vue

src/components/conversation/conversation.vue

src/components/desktop_nav/desktop_nav.scss

src/components/dialog_modal/dialog_modal.vue

src/components/emoji_input/emoji_input.vue