Overlay Notifications

@Sir_Indy Oh, it isn't solely for your benefit ;-) It would also allow me to remove duplicate code from smessages, and just use the default messages library.
I made a PR for message events. With those changes you could do something like this:

// aanotifi.boot.js
Bangle.on("message", (type, message)=> {
      if (type !== "text") return; // let default app handle e.g. "music" or "call"
      require("notify").show(message);
      require("messages").buzz(message.src);
      message.handled = true; // prevent default app from launching    
});