@fluent/bundle 0.15.0

• Migrate to TypeScript. (#436)

  The source code of @fluent/bundle has been ported to TypeScript. There
  are no breaking changes to the public API.

  A new export has been added for TS consumers: FluentValue which is a
  union of the FluentType class and string. This reflects the
  implementation detail of @fluent/bundle which treats primitive strings
  as valid FluentType instances.

  The ES module files are now published into the esm directory. It also
  contains the type definitions for TS consumers. The src directory has
  been removed from the published packages.