Discardable

An interface to be implemented by any Ability that needs to free up the resources it uses.

This discard method is invoked directly by the Actor, and indirectly by Stage:

• when SceneFinishes, for actors instantiated after SceneStarts - i.e. within a test scenario or in a "before each" hook
• when TestRunFinishes, for actors instantiated before SceneStarts - i.e. in a "before all" hook