Global home currency

[scionaltera]

The current implementation assumes USD is your "default" fiat currency, and uses convertExchangePair() all over the place to make a conversion if the exchange is configured to have a different homeCurrency. It would be a really helpful refactor to be able to set a currency at the top level of the configuration rather than in every exchange. For example:

trading:
  entrySpread: 0.008
  exitTarget: 0.0050
  fixedExposure: 30
  fiatCurrency: EUR # use EUR instead of USD as the default fiat currency
  tradeTimeout: 24

  exchanges:

Setting homeCurrency on an exchange configuration should override the fiatCurrency setting. Without this, non-US users are stuck setting homeCurrency for every single exchange.