Updated katex to 0.6.0 and enabled $...$ and $$...$$ syntax

Replace empty links/clickable divs with <button/> (addresses #3045)

Added quote button to messages.

New message editing features

Ability to close livechat rooms

LingoHub Update 

Manual push by LingoHub User: Gabriel Engel.
Project: Rocket.Chat

Made with  by https://lingohub.com

Less reactive livechat app

Correct GitLab service name

fix message composing help

Fix code highlight on code that contains delimiter

- Allows cursor movement across wrapped lines when editing messages
- Saves drafts when editing messages, so switching between them doesn't
  discard changes made so far.
- ESC key discards draft for current message if exists or goes out of
  edit mode if doesn't exist.
- ALT+UP/DOWN to travel whole messages
- Emptying message deletes it

Enables favorite rooms to non-admins