Rename setup.py to cx_setup.py

This is necessary in order to have a standard setup.py for source
installations.
Rename src directory to reggata.
Add a main() function to reggata.py and a launcher file calling main().
Move all source files in reggata folder.
Add an __init__.py with info about the project.
Minor cleanup
move translation files to a separate folder.
Add a setup.py and a launcher file.