Support federation with matrix.org protocol

While we're on that topic, I'm sure a lot of people would be curious to see a README blurb about why Linen wasn't built on Matrix in the first place.

Originally it started out as a project to only make Slack Google searchable and it was quick to build out https://news.ycombinator.com/item?id=31168882

We then evolved it to it's own platform here:
https://news.ycombinator.com/item?id=33248488

We are probably going to have our own matrix bridge in Linen but there are a few features that matrix doesn't have that we do.

• Discord Forum support
• Moving messages between threads and channels (You can do via drag and drop)
• Open/Close states
• 2 way Github issues sync - We can send messages to Github and vise versa
• Mark as resolution

Going forward we'll probably add the following features:

• Labels, assignments
• Custom view types (Forum view/Blog view/Support view)

If we were building on matrix we wouldn't be able to build these features.

The end goal of Linen is to become more than a chat client. We want to bring all the benefits of a forum and chat in one hence the Search-engine friendliness.

I'll be sure to add and improve the readme on some of the end vision of Linen