Git commits in Moodle 3.9.0 by Alexander Bias

commit d4737c214730f74af8e8f280e83390263be62cda
Author: Alexander Bias <alexander.bias@uni-ulm.de>
Date:   Tue, 24 Mar 2020 04:33:47 +0800
Tag:    v3.9.0-beta

MDL-58964 navigation: Reindex array when element is removed

commit 13b6b5dce83992b3c63f1184d8ab0322224a6eef
Author: Alexander Bias <alexander.bias@uni-ulm.de>
Date:   Fri, 20 Mar 2020 03:34:24 +0800
Tag:    v3.9.0-beta

MDL-58964 navigation: Add class attributes to Boost flat navigation