- go doc and go test updated

- Function `SetCellValue()` support `time.Time` data type parameter, relate issue #49;
- go doc and go test updated

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

- go test updated

- go test updated

- Function `GetRows()` doc updated, relate issue #43;
- go test and embed template updated

- Readme updated;
- go test update

- Doc for function `GetRows()` updated, relate issue #43;
- Fix doc typo in `xmlContentTypes.go`;
- Default template updated;
- Readme updated;
- 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

Performance enhancements, remove redundant XML element checking logic. Relate issue #29. The benchmark report of the current version of this library is shown on the wiki page.

- go test updated

- Set text in cell align support, note that the parameters of the `SetCellStyle` function have changed;
- go test updated

- go test updated

- Rename function `SetBorder` to `SetCellStyle`;
- Complete `xlsxColor` structure definition;
- go test updated

- Partial logic performance optimization, use pointer reference instead of a pass the variable value;
- Add comments for content types struct definition;
- Update go test `TestSetBorder` section

- Function parameter code is simplified;
- Fix element `Tint` value parsing error in worksheet;
- Update go test

Standard io.Reader and io.Writer capabilities

- Improved performance when reading large files, call Token to read tokens one by one instead Unmarshal. Related issue #20 ;
- Fix go test typo;
- Update README

Add SetRowHeight function

Make functions: `SetCellValue`, `SetCellInt`, `SetCellHyperLink`, `SetCellFormula`, `GetCellValue` and `GetCellFormula` to support the merged cells.