Merge branch 'jirka/maily' into 'devel'

etc/config.py.example

mo/web/org_contest.py

mo/web/org_round.py

mo/web/templates/base.html

mo/web/templates/doc_about.html

mo/web/templates/doc_gdpr.html

mo/web/templates/org_contest_list.html

mo/web/templates/org_round_list.html

mo/web/templates/parts/org_participants_emails.html

mo/web/templates/parts/org_participants_table_actions.html