1.3.4: Fix - Upgrade PyYaml for security reasons

In PyYAML before 4.1, the yaml.load() API could execute arbitrary code.

Spanish translation, russian and chinese text handling

• Permit to have our own static file and not conflict with other project static file.
• PySankey is now a third party library
• Apply black and isort style automatically for contributors.

Python 3+ only

Fix the installation bug of 1.3.0.

Thanks to Javier Ordóñez for the report.

Compatible with python 2.7

Fix the installation bug of 1.2.2.

Thanks to Javier Ordóñez for the report.