Currency Converter - Real-time Exchange Rate

Currency Converter support for conversion between multiple currencies.

- Support to refresh the real time exchange rate;
- Support save calculation history;
- Support setting basic currency from six common currencies;
- Support for conversion between 23 currencies:

- USD
- EUR
- GBP
- CAD
- CNY
- AUD
- JPY
- RUB
- KRW
- SEK
- SGD
- THB
- TWD
- BRL
- CHF
- DKK
- HKD
- IDR
- MOP
- MYR
- NOK
- NZD
- PHP