updated core to 1.7.15

system/src/Grav/Installer/updates/1.7.0_2020-11-20_1.php

@@ -0,0 +1,24 @@
+<?php
+
+use Grav\Installer\InstallException;
+use Grav\Installer\VersionUpdate;
+use Grav\Installer\YamlUpdater;
+
+return [
+    'preflight' => null,
+    'postflight' =>
+        function () {
+            /** @var VersionUpdate $this */
+            try {
+                // Keep old defaults for backwards compatibility.
+                $yaml = YamlUpdater::instance(GRAV_ROOT . '/user/config/system.yaml');
+                $yaml->define('twig.autoescape', false);
+                $yaml->define('strict_mode.yaml_compat', true);
+                $yaml->define('strict_mode.twig_compat', true);
+                $yaml->define('strict_mode.blueprint_compat', true);
+                $yaml->save();
+            } catch (\Exception $e) {
+                throw new InstallException('Could not update system configuration to maintain backwards compatibility', $e);
+            }
+        }
+];