Python target overly mangles class names, removes modules

I understand the historical and practical reasons for the design of the python target. The code runs perfectly fine if my aim is to make a python file to feed into the interpreter. However, as all code is placed in the same file, namespaces and classes are all concatenated together. If there was an option to output multiple files in appropriate directories, like `--py-separate-files`, then the class and namespace names can remain true to the original (python works similar to haxe in this regard) and the output can be more suitable to ship as a pip package. If this is a change that you all would be interested in but too busy to implement yourselves I may be interested in learning ocaml in order to make a PR for this.