Add categories template and ok to add one category in db, next modify and delete.

src/lib/Category.php

@@ -0,0 +1,24 @@
+<?php
+
+namespace Garradin\Plugin\Materiels;
+
+use Garradin\Entity;
+use Garradin\DB;
+
+class Category extends Entity
+{
+  const TABLE = 'plugin_materiels_category';
+
+  protected $id;
+	protected $name;
+
+  protected $_types = [
+    'id' => 'int',
+    'name' => 'string',
+  ];
+
+  static public function listAll(): array
+	{
+		return DB::getInstance()->get('SELECT id, name FROM plugin_materiels_category ORDER BY name COLLATE NOCASE;');
+	}
+}