Calculator -- time, gcd, lcm

Contains a simple standard calculator and add, subtract, multiply and divide units of time is a time calculator. 1. Year, day, hour, minute, and second can be calculated by the calculator. 2. Support mix units of time. Ex. 10h5m5s+5m1h = 11hr 10min 5sec. 3. Support converted button to convert into units of another time style.