MVP implementation for multiple fiat currencies. Some parts of the app had been written assuming hardcoded USD only support, and these had to be refactored.
- Convert fiat price API fetch from ongoing interval to named interval stored in state that can be cleared
- Add new settings parameter to local storage. For now, only fiat currency is here. Going forward this is extensible for other app settings.
- Add function changeCashtabSettings to useWallet.js to update app settings (and lock UI until update is complete)
- Add a select menu to Configure.js to update currencies
- Replace 'USD' with '!== XEC' in comparisons that were checking for fiat or crypto