Git commits in Moodle 3.8.1 by Bas Brands

commit c02d168cd71f56598b6765da19ea3769aa1164fb
Author: Bas Brands <bas@moodle.com>
Date:   Wed, 11 Dec 2019 20:53:21 +0800
Tag:    v3.8.1

MDL-67470 theme_boost: settings_menu_proxy correct background


commit e29b355121fca60ac514e441fbf8626b77491037
Author: Bas Brands <bas@moodle.com>
Date:   Wed, 13 Nov 2019 19:12:52 +0800
Tag:    v3.8.1

MDL-67222 tool_lp: update css classes for Bootstrap 4.3


commit 8c20e76d4332b88503e1c0235d0b76fd398af33f
Author: Bas Brands <bas@moodle.com>
Date:   Tue, 11 Dec 2018 17:53:19 +0800
Tag:    v3.8.1

MDL-63107 mod_book: rewrite styles for book chapter block