fixed phpsh to work with objects implementing Serializable

Summary: current implementation of phpsh usese serialize/unserialize
cycle and some hacks to convert an object into an array. This fails if
the object's class implements the Serializable interface and uses custom
serialization (hacks dont' work). I have fixed this problem by instead
casting objects to arrays and demangiling private and protected key
names.

src/phpsh.php

@@ -223,17 +223,16 @@ function ___phpsh___parse_dump_obj_lines($x, $dump, &$pos, $arr_len, $depth,
     return $arr_lines;
   }
   function ___phpsh___obj_to_arr($x) {
-    $x_ser = serialize($x);
-    $x_ser = substr($x_ser, strpos($x_ser, ':', 3) + 1);
-    $x_ser = 'a'.substr($x_ser, strpos($x_ser, ':'));
-    $x_arr = array();
-    foreach (unserialize($x_ser) as $k => $v) {
-      if ($k[0] == "\000") {
-        $k = substr($k, strpos($k, "\000", 2) + 1);
+    if (is_object($x)) {
+      $raw_array = (array)$x;
+      $result = array();
+      foreach ($raw_array as $key => $value) {
+        $key = preg_replace('/\\000.*\\000/', '', $key);
+        $result[$key] = $value;
       }
-      $x_arr[$k] = $v;
+      return $result;
     }
-    return $x_arr;
+    return (array)$x;
   }
   function ___phpsh___parse_dump_assert($dump, &$pos, $str, $end=false) {
     $len = strlen($str);