constructor(plugin) {
        this.plugin = plugin;

        this.about = null;
        this.summary = null;
        this.errors = [];

        this.$el = null;
    }
The following code defines an information panel that can be invoked from
any plugin to display summaries, errors, or more information about what
the plugin is doing.

These panels are moveable and closeable, and are unique to the plugin that
created them. They appear in the bottom right corner of the viewport.

Info panels consist of a title and three optional sections, which form
tabs that users can switch between.

  Summary: A summary of the plugin's results
  Errors: A list of violations reported by this plugin. The tab marker also
          contains the number of errors listed