* Add example atari_iqn_hl
* Factor out trainer callbacks to new module atari_callbacks
* Extract base class for DQN-based agent factories
* Improved module factory interface design, achieving higher generality
* Changed machanism for reusing actor's preprocessing module in critics
to avoid special handling in AgentFactory implementations, improving
separation of concerns:
- Added CriticFactoryReuseActor as the new critic factory
- Added ActorFactoryTransientStorageDecorator to pass on the actor
data
- Added helper classes ActorFuture, ActorFutureProviderProtocol
* Add example atari_sac_hl
* Implement example mujoco_redq_hl
* Add abstraction CriticEnsembleFactory with default implementations
to suit REDQ
* Fix type annotation of linear_layer in Net, MLP, Critic
(was incompatible with REDQ usage)
After adding a function to create ModuleOpt instances directly from
AgentFactory and CriticFactory,
* several mixins for AgentFactories are no longer needed (deleted)
* additional abstractions for ModuleOptFactories are no longer needed (deleted)
* Allow to specify trainer callbacks (train_fn, test_fn, stop_fn)
in high-level API, adding the necessary abstractions and pass-on
mechanisms
* Add example atari_dqn_hl
