Use WordPress Categories in Events Manager

<?php
/**
 * This function enables WordPress Categories in Events Manager.
 *
 * This will also automatically enable dropdown for easy filtering
 * in the Events Admin List before the Events Scope dropdown.
 */
function stonehenge_em_use_wp_categories() {
    register_taxonomy_for_object_type( 'category', 'event' );
    register_taxonomy_for_object_type( 'category', 'event-recurring' );

    # Uncomment the line below to also use for Events Manager Locations.
    //register_taxonomy_for_object_type( 'category', 'location' );
}
add_action( 'init', 'stonehenge_em_use_wp_categories', 20 );