refinements in drupal-site-install core plugin
refinements in drupal-site-rollback core plugin
refinements in drupal-site-update core plugin
refined deleteBuild() to use new DrupalSiteEvent class
basic refinements to the drush-backup plugin
added new rollback steps targeted at subsites
refinements to the update/delete parts of the drush-backup plugin
refinements to the rollback parts of the drush-backup plugin