* [bug] set errno=0 when ForceDirectories is successful(result=0)
- remove unused variable.
* idbErrorStr: + convert the errno error.
+ iIncrByInFile can return error via error now.
* [bug] IncrByDirValue is not work well.
* [bug] assert typo
+ iDB IsExistsInFileSync, IncrByInFileSync/Async functions, Constants and tests