API Upgrade CMS to use new Config API

_config/routes.yml

@@ -1,7 +1,6 @@
 ---
 Name: modelascontrollerroutes
-Before: '*'
-After: '#rootroutes'
+After: '*'
 ---
 SilverStripe\Control\Director:
   rules:
@@ -11,7 +10,6 @@ SilverStripe\Control\Director:
     '$URLSegment//$Action/$ID/$OtherID': 'SilverStripe\CMS\Controllers\ModelAsController'
 ---
 Name: legacycmsroutes
-After: '#adminroutes'
 ---
 SilverStripe\Control\Director:
   rules:

code/Controllers/CMSMain.php

@@ -952,7 +952,7 @@ class CMSMain extends LeftAndMain implements CurrentPageIdentifier, PermissionPr
         $gridFieldConfig = GridFieldConfig::create()->addComponents(
             new GridFieldSortableHeader(),
             new GridFieldDataColumns(),
-            new GridFieldPaginator(self::config()->page_length)
+            new GridFieldPaginator($this->config()->get('page_length'))
         );
         if ($parentID) {
             $linkSpec = $this->Link();

code/Controllers/CMSPageEditController.php

@@ -8,7 +8,6 @@ use SilverStripe\CMS\Model\SiteTree;
 use SilverStripe\Control\Controller;
 use SilverStripe\Control\HTTPRequest;
 use SilverStripe\Control\HTTPResponse;
-use SilverStripe\Core\Convert;
 use SilverStripe\Forms\Form;
 use SilverStripe\ORM\FieldType\DBHTMLText;
 

code/Model/SiteTree.php

@@ -1573,7 +1573,7 @@ class SiteTree extends DataObject implements PermissionProvider, i18nEntityProvi
             ));
         }
 
-        $charset = ContentNegotiator::config()->get('encoding');
+        $charset = ContentNegotiator::config()->uninherited('encoding');
         $tags[] = FormField::create_tag('meta', array(
             'http-equiv' => 'Content-Type',
             'content' => 'text/html; charset=' . $charset,

code/Model/VirtualPage.php

@@ -102,7 +102,10 @@ class VirtualPage extends Page
      */
     public function getNonVirtualisedFields()
     {
-        return array_merge($this->config()->non_virtual_fields, $this->config()->initially_copied_fields);
+        return array_merge(
+            VirtualPage::config()->non_virtual_fields,
+            VirtualPage::config()->initially_copied_fields
+        );
     }
 
     public function setCopyContentFromID($val)
@@ -417,7 +420,7 @@ class VirtualPage extends Page
      * Pass unrecognized method calls on to the original data object
      *
      * @param string $method
-     * @param string $args
+     * @param array $args
      * @return mixed
      */
     public function __call($method, $args)