Refactor model property in mbchac class and HLEnv Class
Problem: In MBCHAC and HLEnv the MBCHAC layers are called 'model', which is ambiguous because the methods for each layer (e.g. SAC, TD3, DQN) are also called model.
Therefore, call the instances of the MBCHAC class layer
instead. This affects, e.g. the sub_model
--> sub_layer
and parent_model
--> parent_layer
. Take care with the layer
property of MBCHAC which refers to an integer describing the layer number.