refactoring of table database, added script for upgrading to versions >= 2.0, added multi-user support

Signed-off-by: giandonato.inverso@edempg.it <giandonato.inverso@studenti.unimi.it>

src/forms/qrcode_options.php

@@ -80,4 +80,29 @@
     </div>
   </div>
 </div>
+
+<?php if($_SESSION['type'] ===  'super') { ?>
+    <div class="col-sm-12 mb-2">
+        <div class="row">
+            <div class="col-sm-4">
+                <div class="form-group">
+                    <label for="id_owner">Owner *</label>
+                    <select name="id_owner" class="form-control">
+                        <option value="" selected>All</option>
+                        <?php
+
+                        require_once BASE_PATH . '/lib/Users/Users.php';
+                        $users_instance = new Users();
+                        $users = $users_instance->getAllUsers();
+
+                        foreach ($users as $user) {
+                            ?>
+                            <option value="<?php echo $user["id"];?>"><?php echo $user["username"];?></option>
+                        <?php } ?>
+                    </select>
+                </div>
+            </div>
+        </div>
+    </div>
+<?php } ?>
     <br>