--format takes text, json, csv, tsv or ics. --json and --ics stay as
shorthand, because the widgets already call them.
csv and tsv are RFC 4180 quoted, one header row, one row per day, with
commemorations joined by a semicolon: a cell that is itself a table is worse
than a cell you have to split. --list-fields prints the twenty columns,
--fields picks a subset in the order you name them, and a column that does
not exist is caught before anything is printed rather than silently emitting
an empty cell.
--no-emoji drops the glyphs from every format, including the emoji field in
the JSON, and collapses the column in the text output rather than leaving a
hole where a glyph used to be.
