Allow searching for users in the user list.

Squashed commit of the following:

commit 46595b7ae0bccfc8e5252daf8101e59ff53fdcdf
Author: Ramón Cahenzli <rca@psy-q.ch>
Date:   Thu Nov 16 19:12:11 2017 +0100

    Preserve search terms and sort order

commit 5445816f1dd7e7de876e226cf8479660a92c07ad
Author: Ramón Cahenzli <rca@psy-q.ch>
Date:   Thu Nov 16 18:53:43 2017 +0100

    First working user search.

commit 620b9787ef7998c4bf219d25075e35f4cfa3d1ee
Author: Ramón Cahenzli <rca@psy-q.ch>
Date:   Thu Nov 16 16:06:37 2017 +0100

    Moving user search to its own action

commit 0c17ac2428c2b38c9535f7a63f8be7582e4e332b
Author: Ramón Cahenzli <rca@psy-q.ch>
Date:   Thu Nov 16 14:58:34 2017 +0100

    WIP on user search, adding search form

app/Controller/UserListController.php

@@ -2,6 +2,8 @@
 
 namespace Kanboard\Controller;
 
+use Kanboard\Filter\UserNameFilter;
+
 /**
  * Class User List Controller
  *
@@ -24,4 +26,35 @@ class UserListController extends BaseController
             'paginator' => $paginator,
         )));
     }
+
+    /**
+     * Search in users
+     *
+     * @access public
+     */
+    public function search()
+    {
+        $search = urldecode($this->request->getStringParam('search'));
+        $paginator = $this->userPagination->getListingPaginator();
+
+        if ($search !== '' && ! $paginator->isEmpty()) {
+
+            $paginator = $paginator
+                ->setUrl('UserListController', 'search', array('search' => $search))
+                ->setQuery($this->userQuery
+                    ->withFilter(new UserNameFilter($search))
+                    ->getQuery()
+                )
+                ->calculate();
+        }
+
+        $this->response->html($this->helper->layout->app('user_list/listing', array(
+            'title' => t('Users').' ('.$paginator->getTotal().')',
+            'values' => array(
+                'search' => $search,
+            ),
+            'paginator' => $paginator
+        )));
+    }
+
 }

app/Template/user_list/header.php

@@ -1,3 +1,4 @@
+
 <div class="table-list-header">
     <div class="table-list-header-count">
         <?php if ($paginator->getTotal() > 1): ?>
@@ -9,4 +10,4 @@
     <div class="table-list-header-menu">
         <?= $this->render('user_list/sort_menu', array('paginator' => $paginator)) ?>
     </div>
-</div>
+</div>

app/Template/user_list/listing.php

@@ -17,6 +17,18 @@
     <?php endif ?>
 </div>
 
+
+<div class="filter-box margin-bottom">
+    <form method="get" action="<?= $this->url->dir() ?>" class="search">
+        <?= $this->form->hidden('controller', array('controller' => 'UserListController')) ?>
+        <?= $this->form->hidden('action', array('action' => 'search')) ?>
+
+        <div class="input-addon">
+            <?= $this->form->text('search', $values, array(), array('placeholder="'.t('Search').'"'), 'input-addon-field') ?>
+        </div>
+    </form>
+</div>
+
 <?php if ($paginator->isEmpty()): ?>
     <p class="alert"><?= t('No users found.') ?></p>
 <?php elseif (! $paginator->isEmpty()): ?>