Pr algorithm container (#858)

* Algorithm container

* Fixes for algorithm/contrainers.py

* Fix algorithms/containers and unittest

* loss_weight for LossAlg

* Loss for EncodingAlgorithm

* AlgorithmInterface

Unify interface for Algorithm and RLAlgorithm

* Update agent to use the new algorithm interface & fix EchoAlg bug

* Cleanup and update SacAlgorithm

* Update other algorithms

* Fix tests

* More tests and comments

* Address comments

* Address more review comments

* Fix comments