Power not correctly scaled with dt

[JanJamaszyk]

Hi Aaren,

first of all thanks a lot for this awesome clean implementation, it's a pleasure to use!
I realized yesterday that somehow my power values where off quite a lot (using unbias=True), which I was able to fix by just scaling the powers by dt. I am not sure where one would need to fix this ideally within the library (maybe some other values are affected as well?) otherwise I would have raised a pr directly ;-).

Greetings