Update the Python implementation with latest good practices

[hugoqnc]

The language support for Python was written before some general changes were introduced.
It should therefore be updated to take advantage of these changes, to have a more coherent and maintainable implementation.

• Rewrite how values are resolved to make it closer to the Java implementation
  • Use ValueActionFactory to capture the function names
• Refactor the translation similarly to what was done with JavaTranslationProcess
  • Add a reorganization layer if necessary

[n1ckl0sk0rtge]

Fixed by #106, #109, #115, #119