Add Briar headless client that exposes a REST API
This is a minimal version of a headless client. It only supports listing/writing private message and blog posts. There's rudimentary support for listing other
PrivateMessageHeaders and receiving them via a websocket to see how the APIs would pan out.
To get a first overview, I suggest to lock at the
README.md which is already included.
It is written completely in Kotlin. Please don't hesitate to ask questions regarding Kotlins language features!