Mail · Boxes and lists: mailboxes, folders and labels, the mail list, inbox zero

MailboxList sets mailboxes, folders and labels in sections: a press, an
arrow or Enter opens one, the open one lit; a box with mail unread
stands out with its count, and a label wears one of the theme's chart
hues. MailList holds messages in a multiple-select list: the sender
strong beside a dot while unread, the subject and first words under
it, the time today, the weekday this week, the date this year or with
its year, a paperclip for files, and a star whose press stays off the
row. InboxZeroState points to feedback::EmptyState.

Sections of selectable lists now have one home, lists::Sections, which
ChannelList and MemberList use too; ListItem gains a third line.

src/lists/mod.rs

@@ -4,6 +4,7 @@ mod grouped;
 mod item;
 mod long;
 mod outline;
+mod sections;
 mod select;
 mod sortable;
 mod swipe;
@@ -19,6 +20,7 @@ pub use grouped::GroupedList;
 pub use item::{List, ListItem};
 pub use long::{InfiniteList, VirtualList};
 pub use outline::Outline;
+pub(crate) use sections::Sections;
 pub use select::SelectableList;
 pub(crate) use select::{Pick, picked};
 pub use sortable::SortableList;