Moves datepicker back to footer.

Moved to head in f7952fe, in order to allow events to fire on keypress. However, for some reason, these are now not firing at all when in head. Not sure what has changed, needs exploration.

See #589

src/my-calendar-core.php

@@ -677,7 +677,7 @@ function mc_register_scripts() {
 	wp_register_script( 'duet.js', plugins_url( 'js/duet/duet.js', __FILE__ ), array(), $version );
 	wp_register_style( 'duet.css', plugins_url( 'js/duet/themes/default.css', __FILE__ ), array(), $version );
 	// Enqueue datepicker options.
-	wp_register_script( 'mc.duet', plugins_url( 'js/mc-datepicker.js', __FILE__ ), array( 'duet.js' ), $version );
+	wp_register_script( 'mc.duet', plugins_url( 'js/mc-datepicker.js', __FILE__ ), array( 'duet.js' ), $version, true );
 	$url = ( SCRIPT_DEBUG ) ? plugins_url( 'js/jquery.admin.js', __FILE__ ) : plugins_url( 'js/jquery.admin.min.js', __FILE__ );
 	wp_register_script( 'mc.admin', $url, array( 'jquery', 'jquery-ui-sortable', 'wp-a11y' ), $version );
 	wp_register_script( 'mc.admin-footer', plugins_url( 'js/admin.js', __FILE__ ), array( 'wp-a11y', 'clipboard' ), $version, true );