Introduction of active elements to contol system

[klaus1956]

With view to variable electricity prices it would be great to get 2 active control entities for the Senec power storage:

• Load from Grid (to store power in times with low prices)
• Stop discharge (to prevent losing charge in times with low price to e.g. Heat Pumps or Non_Senec Chargers

Both options seem to be available manually for Senec-Technicans