Review LIQSS methods state and engine interactions.

[joaquinffernandez]

Task
Currently the Quantizer state has a lot of LIQSS definitions that are not clear, most of them are used to define the interactions between the method and the engine, for instance to trigger instant steps in mLIQSS methods.
This task is to clarify the state meaning in the quantizer and make clear the actions taken in LIQSS methods.