Calendar, task list and address book choosers are grouped under each
account's address, the sidebar and Settings head each account by its
address, and a second account's default calendar gets a colour of its
own. Events can no longer go into a task list from the editor, quick
create or import; the task editor's "List" offers task lists only. New
events preselect the active account's last-used or default calendar,
and the event menu has "Copy to <address>" for the other account.
Two task editor tests change their fixtures and label: the select now
lists task lists only and is labelled "List", so plain calendars no
longer appear in it (pim-p2-13).