* rename .stylelintrc to .stylelintrc.json for explicit file type
* add new npm script lint-fix:style
* fix pseudo-element with double colon
* function name should be lower except ignored functions
* support stylelint declaration-block-no-ignored-properties rule
* support sorted CSS properties order for readability and consistency
* autofix order of all styles by lint-fix:style script
* remove double slash comments after selector
* replace .stylelintignore with ignoreFiles in .stylelintrc.json
* Remove span.ant-tag-text
Warp React.ReactNode with span element is not suggested. It may cause anti-specification problem: `<span><span>I'm spec breaker</span></span>`. span is not a general tags container.
Another benefit from this change is keeping the same structure with CheckableTag.
After inspecting the removing of the style of .ant-tag-text, seems bringing no problems. The old example employeed this css class has gone long long time ago. See: 0635877a51
* Use React.Children.only api to supress type casting
By codes, the children and the overlay of Dropdown must be **single** and **valid React.ReactElement**. React.Children.only takes it and report more friendly React internal built error messages.
* Revert hack CSS styles: filling .ant-tag's block area with orphan child anchor