[MERGE] forward port branch 9.0 up to 9ba56987

addons/account/models/account_invoice.py

addons/calendar/calendar.py

addons/hr_expense/models/hr_expense.py

addons/hr_holidays/hr_holidays.py

addons/mail/models/mail_template.py

addons/mail/wizard/mail_compose_message.py

addons/website/static/src/js/website.js

addons/website_blog/static/src/js/website_blog.editor.js

addons/website_sale/static/src/css/website_sale.css

addons/website_sale/static/src/css/website_sale.sass

doc/cla/individual/mcb30.md

doc/setup/install.rst