message: focus the composer in the body keydown handler if not other shortcuts apply
  this allows the user to start typing a message even if the composer is not focused.
diff: @@ -333,6 +333,22 @@ const LoggedInView = React.createClass({
  if (handled) {
  ev.stopPropagation();
  ev.preventDefault();
  + } else {
  + const targetTag = ev.target.tagName;
  + const focusedOnInputControl = targetTag === "INPUT" ||
  + targetTag === "TEXTAREA" ||
  + targetTag === "SELECT" ||
  + ev.target.getAttribute("contenteditable");
  + // we don't check for buttons that have focus here,
  + // because they should be using AccessibleButton which
  + // calls stopPropagation on space or enter keydown, so
  + // that keydown event would never get here.
  + if (!focusedOnInputControl) {
  + dis.dispatch({action: 'focus_composer'}, true);
  + ev.stopPropagation();
  + // we should *not* preventDefault() here as
  + // that would prevent typing in the now-focussed composer
  + }
  }
  },
  