Matrix support and teams shared accross accounts

This is a two parter, firstly and primarily I think adding support for the open source chat protocol matrix .org this could help serve as a way of integrating Ryver with other chat systems when you need to communicate with someone who doesn't want to or can't use Ryver for some reason. Could probably work with most other chats and there are already support for many like Slack, Twitter, IRC etc.

For the second part, Ryver could support adding a channel that exists on two different accounts at the same time so if two companies need to cooperate and both use Ryver they can have a common channel instead of one of them inviting all the others as guests. By implementing Matrix support I think this could be achieved. Maybe an even better solution could be made with your own protocol alone but this would be an added benefit to supporting Matrix and should not need any additional work.