- go test updated

Adds a '{' to the example for sheet.GetSheetMap()
Signed-off-by: NMark Stenglein <mark@stengle.in>

- Make function `TitleToNumber()` exportable, note that function `ToAlphaString()` return value calculation changes, get more info from go doc. Relate issue #63;
- Readme and go doc updated

- go test updated

- Drawing `nvPicPr` element ID property calculation changed;
- go test updated

- go test updated

- Typo fixed;
- go test updated

Fix return index error in function `GetSheetMap()`;
Fix return worksheet name error in function `GetSheetName()`;
go test updated

- Optimize deserialization operations;
- README updated, add go version required notice

- go test updated

- go test updated

- Character limits for cells added;
- Update go test and fix typo

- Add escape characters of sheet name;
- Update go test and fix typo

- New functions `GetActiveSheetIndex`, `GetSheetName` and `GetSheetMap` added.

- Update workbook and sheet relationships and self-close tag replacement hack functions

- Compatibility improved: relationship namespace in `workbook.xml` has been changed (`xmlns:mc`, `xmlns:x15` and `mc:Ignorable` added)

- Fix issue XML tag `headerFooter` and `sheetPr` element self-close errors cause file corruption;
- Fix issue `Section` and `Pane` element order make file corruption in some case;
- Change sheet `rId` calculation method in `/xl/workbook.xml`, fix makes file corruption in some case;
- Compatibility improved: add `xlsxTabColor` struct and some XML element for worksheet

- Update import PKG syntax in struct;
- Update test XLSX file (include table, charts, functions, comments and hyperlink on Sheet1)

- Update test template for this fix

Fix hyperlink missing after save issue and update completion row element logic to enhance compatibility.

- Optimisation code use fmt package
- Update README
- Remove useless function