- Rename exported field `File.XLSX` to `File.Pkg`
- Exported error message

This closes #861, support concurrency get cell picture and remove unused internal function `getSheetNameByID`

- Fix incorrect scope when getting defined name
- Update docs: use column number instead of index on get column width

make the caller of `getRowHeight` function adapt row number change, update comment: use rows number instead of rows index.

- Note that: travis-ci.org will shutdown on June 15th, 2021, and I don't have enough permission to migrate this project to travis-ci.com currently

* fixes https://github.com/360EntSecGroup-Skylar/excelize/issues/858

* fixes https://github.com/360EntSecGroup-Skylar/excelize/issues/858Co-authored-by: Ndvelderp <peter.de.velder@gmail.com>

According to issue #409

There is absolutely no reason for the timezone to be in UTC, and converting the local times to UTC while keeping values is hacky at least.

Excel has no understanding of timezones, hence the user of this library should know what timezone their values are supposed to be, by following the timezone within their timeTime structs.

feat: add disable option for chart xAxis and yAxis

fix the bug that  there was no count attribute in sharedStrings file, fix the bug that setting OutlineSummaryBelow false

* "15" is the correct 24 hours time format in go
* fix number format convert issue and remove the `dateTimeFormatsCache`

This closes #652, new SetColWidth API, support set column width in stream writing mode, and export error message