This type allows for updating a cell's value, including Date for convenience.
As with ScalarUpdate, null can be used to clear the cell's value.
A rich value may be given as its JSON ({ type, data }, what IRichData.toJSON
returns); it is made by the kind registered for type, and an unregistered type is kept
as it was given.
Represents an update to a cell's value in JavaScript, allowing
Date, a rich value's JSON andnull.