SMS Thread Display, Message Editing etc

In a previous post, I got Unicode text rendering, complete with line breaking, emojis and a pile of other stuff working, that means we can show message threads. Now we need to refactor that out into some thing more usable, and add the missing bits. Like being able to type a message, hit send, have a functional scroll-bar etc. Then we'll have almost an entire working SMS system, sans talking to the…