v4.4.0 - Fix update currency rate issue
v4.3.0 - Show version information
v4.2.0 - Fix backspace button issue
v4.1.0 - Change language function
Features:
* Support many types of unit (weight, length, area, volume/capacity, temperature, power, speed, pressure, computer memory units)
* Multi-country currency conversion (auto update exchange rate)
* Supports the units of measurement commonly used in Asia (for example: Hong Kong's tael, China's catty, Taiwan's ping, Japan's jian)
* Real-time conversion (Keep updating the result when user is updating the input)
* Automatically save the last used unit, so that you can use it faster next time
* Support negative number
* Support portrait and landscape interface
* Support three languages (Traditional Chinese, Simplified Chinese, English)
