fixes data/null component bug by assigning default values for the _inwards and _outwards class attributes of the framework components SurfaceLayerComponent/SubSurfaceComponent/OpenWaterComponent (default value being the list of keys of their respective _inwards_info and _outwards_info class attributes, i.e. assuming that the whole set of inward/outward transfers is used/produced.
adds unit test to check the new behaviour above when instantiating data/null component
adds doc test in MetaComponent to check for the correct component metaclass display (through printing the component class itself)
resolve #87
This PR:
_inwardsand_outwardsclass attributes of the framework componentsSurfaceLayerComponent/SubSurfaceComponent/OpenWaterComponent(default value being the list of keys of their respective_inwards_infoand_outwards_infoclass attributes, i.e. assuming that the whole set of inward/outward transfers is used/produced.