Trying to make progres on persisting selection state, restoring selection state for new multi variable dropdown, proving to be really complex

More work on tags in variable dropdown, now the actual tag values query is hooked up and works, #2080

Fixed typos

new role Read Only Editor - admin (small fix for #2088)

User role 'Viewer' are now prohibited from entering edit mode (and doing other transient dashboard edits). A new role  will replace the old Viewer behavior

Use private email address in GitHub OAUTH

update docs for configration: allowed_domains

GitHub users without a public email should be authenticated using their primary private email address