Correct cells style in merge range
Fix incorrect style ID returned on getting cell style in some cases
Unit test updated and simplified code

Fix file corrupted when save as in XLAM / XLSM / XLTM / XLTX extension in some case
New exported error ErrWorkbookExt has been added, and check file extension on save the workbook
Format source code with `gofumpt`

Rename exported constants `NameSpaceDublinCoreMetadataIntiative` to `NameSpaceDublinCoreMetadataInitiative`

- Unzip shared string table to system temporary file when large inner XML, reduce memory usage about 70%
- Remove unnecessary exported variable `XMLHeader`, we can using `encoding/xml` package's `xml.Header` instead of it
- Using constant instead of inline text for default XML path
- Rename exported option field `WorksheetUnzipMemLimit` to `UnzipXMLSizeLimit`
- Unit test and documentation updated

- Close spreadsheet and row's iterator required
- New options `WorksheetUnzipMemLimit` have been added
- Improve streaming reading performance, memory usage decrease about 93.7%

- Make variable name more semantic
- Reduce cyclomatic complexities for the formula calculate function
- Support specified unzip size limit on open file options, avoid zip bombs vulnerability attack
- Typo fix for documentation and error message

- 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`

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.

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

typo fixed

lint issue fixed and new formula function: ATAN, AVERAGE, AVERAGEA, CONCAT, CONCATENATE, COUNT, COUNTBLANK, MAX

* extend cell value load to support custom datetime format

* cleanup incorrect imports

* fix numeric values conversion as done in legacy Excel

* fix tests coverage

* revert temporary package name fix

* remove personal info from test XLSX files

* remove unused dependencies

* update format conversion in parseTime

* new UT to increase code coverage

* Resolve code review issue for PR #703

* Rename broken file name generated by unit test
Co-authored-by: xuri <xuri.me@gmail.com>

-  added 3 internal function: getSheetID, getActiveSheetID, getSheetNameByID

Resolve #580, revert commit https://github.com/360EntSecGroup-Skylar/excelize/commit/5ca7231ed408ac264f509ff52b5d28ff4fbda757