Add missing use lines, fix some class names, remove unused use lines

src/Admin/SubsiteAdmin.php

@@ -3,6 +3,8 @@
 namespace SilverStripe\Subsites\Admin;
 
 use SilverStripe\Admin\ModelAdmin;
+use SilverStripe\Forms\GridField\GridFieldDetailForm;
+use SilverStripe\Forms\GridField\GridFieldPaginator;
 use SilverStripe\Subsites\Forms\GridFieldSubsiteDetailForm;
 use SilverStripe\Subsites\Model\Subsite;
 
@@ -29,8 +31,9 @@ class SubsiteAdmin extends ModelAdmin
     {
         $form = parent::getEditForm($id, $fields);
 
-        $grid = $form->Fields()->dataFieldByName(Subsite::class);
+        $grid = $form->Fields()->dataFieldByName(str_replace('\\', '-', Subsite::class));
         if ($grid) {
+            $grid->getConfig()->getComponentByType(GridFieldPaginator::class)->setItemsPerPage(100);
             $grid->getConfig()->removeComponentsByType(GridFieldDetailForm::class);
             $grid->getConfig()->addComponent(new GridFieldSubsiteDetailForm());
         }

src/Forms/GridFieldSubsiteDetailForm.php

@@ -6,5 +6,5 @@ use SilverStripe\Forms\GridField\GridFieldDetailForm;
 
 class GridFieldSubsiteDetailForm extends GridFieldDetailForm
 {
-    protected $itemRequestClass = GridFieldSubsiteDetailFormItemRequest::class;
+    protected $itemRequestClass = GridFieldSubsiteDetailForm_ItemRequest::class;
 }

src/Forms/SubsitesTreeDropdownField.php

@@ -4,7 +4,6 @@ namespace SilverStripe\Subsites\Forms;
 
 use SilverStripe\Control\Controller;
 use SilverStripe\Control\HTTPRequest;
-use SilverStripe\Control\Session;
 use SilverStripe\Core\Manifest\ModuleLoader;
 use SilverStripe\Forms\TreeDropdownField;
 use SilverStripe\View\Requirements;

src/Model/Subsite.php

@@ -8,26 +8,20 @@ use SilverStripe\Control\Director;
 use SilverStripe\Control\Session;
 use SilverStripe\Core\Convert;
 use SilverStripe\Core\Injector\Injector;
-use SilverStripe\Forms\CheckboxField;
+use SilverStripe\Dev\Deprecation;
 use SilverStripe\Forms\CheckboxSetField;
 use SilverStripe\Forms\DropdownField;
 use SilverStripe\Forms\FieldList;
 use SilverStripe\Forms\GridField\GridField;
 use SilverStripe\Forms\GridField\GridFieldConfig_RecordEditor;
-use SilverStripe\Forms\HeaderField;
 use SilverStripe\Forms\HiddenField;
-use SilverStripe\Forms\LiteralField;
 use SilverStripe\Forms\Tab;
-use SilverStripe\Forms\TabSet;
-use SilverStripe\Forms\TextField;
 use SilverStripe\Forms\ToggleCompositeField;
-use SilverStripe\i18n\Data\Intl\IntlLocales;
-use SilverStripe\i18n\i18n;
 use SilverStripe\ORM\ArrayLib;
 use SilverStripe\ORM\ArrayList;
+use SilverStripe\ORM\DB;
 use SilverStripe\ORM\DataList;
 use SilverStripe\ORM\DataObject;
-use SilverStripe\ORM\DB;
 use SilverStripe\ORM\SS_List;
 use SilverStripe\Security\Group;
 use SilverStripe\Security\Member;
@@ -35,6 +29,8 @@ use SilverStripe\Security\Permission;
 use SilverStripe\Security\Security;
 use SilverStripe\Subsites\State\SubsiteState;
 use SilverStripe\Versioned\Versioned;
+use SilverStripe\i18n\Data\Intl\IntlLocales;
+use SilverStripe\i18n\i18n;
 use UnexpectedValueException;
 
 /**

tests/php/FileSubsitesTest.php

@@ -5,7 +5,6 @@ namespace SilverStripe\Subsites\Tests;
 use SilverStripe\Assets\File;
 use SilverStripe\Assets\Folder;
 use SilverStripe\Forms\FieldList;
-use SilverStripe\Security\Member;
 use SilverStripe\Subsites\Extensions\FileSubsites;
 use SilverStripe\Subsites\Model\Subsite;
 

tests/php/SubsiteAdminFunctionalTest.php

@@ -7,7 +7,6 @@ use SilverStripe\CMS\Controllers\CMSPageEditController;
 use SilverStripe\Core\Config\Config;
 use SilverStripe\Dev\FunctionalTest;
 use SilverStripe\Subsites\Model\Subsite;
-use SilverStripe\Subsites\State\SubsiteState;
 
 class SubsiteAdminFunctionalTest extends FunctionalTest
 {

tests/php/SubsiteXHRControllerTest.php

@@ -2,7 +2,6 @@
 
 namespace SilverStripe\Subsites\Tests;
 
-use SilverStripe\Control\Session;
 use SilverStripe\Dev\FunctionalTest;
 
 class SubsiteXHRControllerTest extends FunctionalTest