0.10.0

• Introduce @factory annotation for methods that must either be abstract or must return a newly allocated object.
• Introduce @literal annotation that indicates that any invocation of a constructor must use the keyword const unless one or more of the arguments to the constructor is not a compile-time constant.

0.9.0

• Introduce @protected annotation for members that must only be called from instance members of subclasses.
• Introduce @required annotation for optional parameters that should be treated as required.
• Introduce @mustCallSuper annotation for methods that must be invoked by all overriding methods.