kraken position tracking gotchas

[goodboy]

As per discussion with @iamzoltan, the kraken api (and frankly their
whole web UI system) is kind of a filthy mess that makes little sense
compared with how most trades would expect to track positions in
different "crypto$ assets" to be presented.

Most of the dirty details are in this article:
https://support.kraken.com/hc/en-us/articles/203325683-Differences-between-spot-exchange-and-margin-trading

The main annoyance is that they don't seem to keep track of spot
position "average price" information for your account and instead
require API users to retrieve past trades and compute their own pp
value.. Why they do offer pp tracking on margin trading positions
but not spot is quite baffling and seems like just poor engineering
(though not surprised, try using their charting platform 😹).

Things that are either confusing af or of note in their api:

• they have "trade ballance" endpoints but only for margin:
  https://docs.kraken.com/rest/#operation/getTradeBalance
  • also wth don't they explain what all the result keys are 😂
• here's where you can pull past spot fills/trades, but they limit to
  50: https://docs.kraken.com/rest/#operation/getTradeHistory

[goodboy]

Pertinent content moved to #515