Fix reference counting

Author: marcospassos

src/main/java/com/marcospassos/phpserializer/Writer.java

@@ -81,6 +81,7 @@ public Writer writeSerializableObjectStart(String className)
         buffer.append("\":");
 
         subWriter = new Writer();
+        subWriter.pointer = pointer + 1;
 
         return subWriter;
     }
@@ -102,7 +103,9 @@ void writeSerializableObjectEnd() {
         buffer.append(data);
         buffer.append("}");
 
-        pointer += subWriter.getPointer();
+        pointer = subWriter.getPointer() + 1;
+
+        subWriter = null;
     }
 
     /**

src/test/java/com/marcospassos/phpserializer/WriterTest.java

@@ -49,7 +49,7 @@ public void writeSerializableObject() throws Exception
         writer.writeSerializableObjectEnd();
 
         assertEquals("C:3:\"Foo\":20:{a:1:{i:0;s:3:\"bar\";}}", writer.getResult());
-        assertEquals(3, writer.getPointer());
+        assertEquals(4, writer.getPointer());
     }
 
     @Test(expected = IllegalStateException.class)