* ✨ support nteract environment.
* 🔨 use temp file in system temp folder
* 🔬 test nteract function and update 📚
* 👕 whitening the code
* 📚 update demo and pump version number
* 📚 give reference to nteract.io
* 📚 update change log and 🐛 a bug fix on tmp file suffix
* Refactor notebook render
1. Merge template files and remove unused files.
2. Move render function to environment class
3. Extract notebook test cases to a new module
* Refactor chart render
1. Add render_* to EchartsEnvironment class
2. Remove engine.render
3. Remove unused template files
* Fix online between test cases.
* Update document and changelog
* Rename some functions
* Update some mistakes
* Remove debug code
* Refactor env.render_chart_to_notebook method
