Massive Update of this branch:

* Change of the steps naming scheme in order to allow importing packages: "from MSNoise.s04stack import stack" works, while "from MSNoise.04.stack doesn't

* First pass of `autopep8` to try to match PEP8 recommendations + manual pass whenever possible

* Added docstrings in most modules to generate the documentation automatically using sphinx (doc not part of this commit)

* added .gitignore settings to ignore .pyc, .log and .sqlite files, and the .build doc folder