Use views_data_alter rather than views_data hook to declare views data

This clears the way for civicrm entities to be declared via the entity api. (at this stage civicrm_views still over-rides any views data declared by that method)

Note that we have been running this fine in production & the one issue is where custom drupal modules extend civicrm_views but their weight is not > 100 (greater than civicrm's weight) they need to have their weight adjusted