Nutrient concentration - WC half/full flush & WM / DW cycle change

[val-ismaili]

for the Wc, I can imagine you would have different values for a full flush (faeces) and half flush (urine). 
For the dishwasher and washing machine you may also want to discern between first discharge (dirt and grease),
second discharge (soap residu added) and 3rd + 4th discharge (mainly water). This may be too much detail for
now, but would be nice to at least have a simple solution in a later version.

Originally posted by @Mirjam-blokker in #72 (comment)