Add "more descendants" indicator and fix indicator draw order

Show small child-box indicators at bottom-right of person cards when
descendants exist beyond the current view. Fix both ancestor and
descendant indicators to draw connecting lines behind boxes.

build/full-diagram/module.php

@@ -0,0 +1,21 @@
+<?php
+
+/**
+ * Full Diagram module for webtrees.
+ *
+ * @license GPL-3.0-or-later
+ */
+
+declare(strict_types=1);
+
+namespace FullDiagram;
+
+use Composer\Autoload\ClassLoader;
+use Fisharebest\Webtrees\Registry;
+
+// Register PSR-4 autoloader for our namespace
+$loader = new ClassLoader();
+$loader->addPsr4('FullDiagram\\', __DIR__ . '/src');
+$loader->register();
+
+return Registry::container()->get(Module::class);