somewhat based on
Electron-Cash/Electron-Cash@b3c76cd31125368f8c216531291c56e188f84245
Electron-Cash/Electron-Cash@adf8f943a1713c21230bb318a3045119c68c241d
Electron-Cash/Electron-Cash@8879e41fa0205b8ff74f359e5477f89185aa0077
- BitcoinAverage seems to have historical rates for all currencies it supports
(as in, if there is spot price, there is also history).
- BitStamp now uses v2 API, also has support for EUR.
- Bitcointoyou does not seem to actually offer histories
(and `request_history` was undefined anyway)
- regenerate currencies.json