Changes since tag v2.8.4

commit 34ad622ea448ceab6baa65385fa8a12986cae5a0
Author: WetU <yuk6196@gmail.com>
Date:   Thu Aug 31 21:11:53 2017 +0900

    Update PlaySound function

commit c5bf8a543a563193ab28890f004d7c0143e39f3f
Author: WetU <yuk6196@gmail.com>
Date:   Thu Aug 31 21:09:51 2017 +0900

    Update PlaySound function in ping module

commit 3465e35b761bf226073f85bc48d6648ffea98529
Author: WetU <yuk6196@gmail.com>
Date:   Thu Aug 31 21:08:18 2017 +0900

    Update PlaySound function in location module

