[Feature Request] Load Balance - Take average card answer time into account

[Thomas47200]

Problem:
When using the load balancing option it creates an even distribution of future due cards like it is supposed to do. Those cards however can come from decks with vastly different average answer times.

So even though there is an even amount of cards due every day, the workload (measured in minutes) can still differ greatly from day to day.

Possible Solution:
When rescheduling, take the average answer time of the corresponding deck of the card into account.

This would create a more balanced load (measured time wise). Altough the number of cards would not be thr same each day any more.