Bug fixes

Fixed some issues and has made code standardization.

# Added styling for book module.
# Added option for slider interval time, dots navigation.
# Added option for "Additional CSS" in theme settings.

Remove usage of deprecated EntityDefinitionUpdateManager->applyUpdates

Issue #3053146 by seonomad: Rules not sending messages

Fix support for certain flex-box layouts in Chrome74.

This is possibly a bug in Chrome74/webkit, but a harmless workaround can be implemented.
https://bugs.chromium.org/p/chromium/issues/detail?id=958802

bugfix: list of no signature roles