v1.3.9
Feature:
- datetime package: add AddYear, BetweenSeconds, DayOfYear, IsLeapYear, IsWeekend.
- fileutil package: add WriteStringToFile, WriteBytesToFile.
- mathutil package: add GCD, LCM, Sin, Cos.
- strutil package: add ContainsAll, ContainsAny, ReplaceWithMap, Trim, SplitAndTrim, HideString.
Fix:
- netutil package: fix bug in functions HttpPost, IsPingConnected.
- datetime package: fix time format issue.