Implement YAML config loader

src/Config/AppConfig.php

@@ -70,10 +70,23 @@ class AppConfig
         return $this->dateTimeFormat;
     }
 
+    public function getTwigCacheDir(): ?string
+    {
+        if (empty($this->twigCacheDir)) {
+            return null;
+        } elseif (substr($this->twigCacheDir, 0, 1) === '/') {
+            // Absolute path
+            return $this->twigCacheDir;
+        } else {
+            // Relative path
+            return ROOT_DIR . '/' . $this->twigCacheDir;
+        }
+    }
+
     public function getTwigSettings(): array
     {
         return [
-            'cache' => $this->twigCacheDir ?: false,
+            'cache' => $this->getTwigCacheDir() ?: false,
             'debug' => $this->isDebugMode(),
             'strict_variables' => $this->isDebugMode(),
         ];