test with more php versions

.travis.yml

@@ -3,11 +3,14 @@ php:
   - 5.3
   - 5.4
   - 5.5
+  - 5.6
+  - 7.0
   - hhvm
 
 matrix:
-    allow_failures:
-        - php: hhvm # due to facebook/hhvm#3321
+  allow_failures:
+    - php: 7.0
+    - php: hhvm # due to facebook/hhvm#3321
 
 env:
   global:

src/File.php

@@ -21,7 +21,7 @@ interface File {
 	public function stream_open($path, $mode, $options, &$opened_path);
 
 	/**
-	 * @param string $offset
+	 * @param int $offset
 	 * @param int $whence
 	 * @return bool
 	 */