Commit 15/07/17:

	- Changing parameter/internal instances variable data structure to dictionary
	- If considered to be a machine, the HBV Model itself is supposed to run correctly
	as long as parameters and inputs are properly given.
	- Under this very demande, the _step_run instance will only have (par, intab) as
	arguments. All other internal procedures will be able to access these arguments.
	- _step_run instance will be temporarily modified as public instance for testing feasibility