[Python/JS/C#] Block Language 2.2.0: Run Polyglot Workflows in One Document

I got tired of writing small glue programs around otherwise simple workflows.

Python was the right tool for data preparation. JavaScript was the right tool for formatting and application logic. Sometimes Lua, PHP, SQLite, or a systems language was the right tool for another stage.

The annoying part was not using multiple languages.

The annoying part was keeping all the boundaries between them alive:

temporary JSON files;