Support php's array callable format for macro's.

This allows you to define methods like this as well: Str::macro('name', [$this, 'method']);

src/Alias.php

@@ -319,10 +319,9 @@ class Alias
                 $properties = $reflection->getStaticProperties();
                 $macros = isset($properties['macros']) ? $properties['macros'] : [];
                 foreach ($macros as $macro_name => $macro_func) {
-                    $function = new \ReflectionFunction($macro_func);
                     // Add macros
                     $this->methods[] = new Macro(
-                        $function,
+                        $this->getMacroFunction($macro_func),
                         $this->alias,
                         $reflection,
                         $macro_name,
@@ -333,6 +332,21 @@ class Alias
         }
     }
 
+    /**
+     * @param $macro_func
+     *
+     * @return \ReflectionFunctionAbstract
+     * @throws \ReflectionException
+     */
+    protected function getMacroFunction($macro_func)
+    {
+        if (is_array($macro_func) && is_callable($macro_func)) {
+            return new \ReflectionMethod($macro_func[0], $macro_func[1]);
+        }
+
+        return new \ReflectionFunction($macro_func);
+    }
+
     /**
      * Output an error.
      *