of number of environments in SamplingConfig is used
(values are now passed to factory method)
This is clearer and removes the need to pass otherwise
unnecessary configuration to environment factories at
construction
* 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
