Banner in web view to show (configurable) information

[turt2live]

Now that we track the target room ID, we should give the option of displaying a banner with information (and #5's delete button).

Example:

banner_options: {
  show_from: true,
  show_subject: true,
  show_timestamp: true,
  show_delete: true
}

... and probably other options.

A better view system is probably needed to accomplish this task.