Hi Bruno,
what do you think if I'll periodically merge stable versions into the master? For example, I think currently the imported 'as is' version can be merged. I'd like to work on API on a separate branch though, since I roughly dislike the idea of developing on master.
For example, see my latest commit; even though it does not affect the API yet, these classes (and similar stuff) are going to replace all this mess with setters and getters, and when it will begin to happen, I don't want to break the current gnulib-tool.py (even though it is considered to be experimental yet).
P.S. I've just started doing the very same thing around Config class that I had done five years ago, but previously it had taken approximately 1000 lines more than now. Wow, just wow.