Each model should have an __init__()

[JortGroen]

After careful consideration, we have decided that the best way forward is to include an init() function in each model to:

• initialise variables and constants
• copy parameters to local variables
• do other stuff

The implications of this are:

• Every model should define an init() function in which it first calls the ModelConsturctor init() super().__init__(**kwargs)
• We will remove the automatic assignment of parameters in ModelConstructor init()
• The above keeps the possibility of allowing multiple model entities per simulator since parameters are not per definition stored in the simulator anymore.