Ability to get cell value by type

[svip]

It would be useful to be able to get cell values as float64 or time.Time (which it is currently possible to set them as), e.g. GetCellFloatValue or GetCellTimeValue. An ability to check type like #417, would help here. An error could be returned if one requested the wrong type. Particularly dates can be hard to parse, considering the date format yielded by Excelize is a bit unusual. And it's not implausible that a user entered such a format as text, meaning some sort of code that wasn't a date. (Honestly, why doesn't Excelize return an ISO formatted time stamp, since it doesn't actually look like the date I see in Excel (which is usually locale based anyway)?)

[xuri]

Thanks for your issue, I have added a new API GetCellType to support get cell data type, please upgrade to the master branch code.