Added

• Style::prefix_formatter and Style::suffix_formatter return Display formatters for the prefix and the suffix of a style, respectively.
• All the *Display types now have an into_styled function that converts those types into a Styled, erasing type parameters.
• Even more methods are now const.

Changed

• The Color and DynColor traits are now explicitly marked sealed (i.e. downstream crates cannot implement them).

  These traits were already effectively sealed due to a number of hidden methods that were not part of the API, but they are now explicitly so. In that sense this is not a breaking change, so it's being released under a new minor version rather than a major version.