Add documentation about deps and remove conda yml

Fix #6 (closed)

I moved from setup.cfg to setup.py to be able to parse dynamically the requirements files instead of duplicating them. This allows also to remove calls to distutils which is deprecated in Python 3.10 and will be removed in Python 3.12.

It is now possible to install daiquiri using:

pip install .[test|doc]

and specifiy test and/or doc to install the test/doc requirements.

I tried first to use a strategy based on conda.yml files but this led to conflicts in the package installations... I therefore removed conda-environment.yml.

After discussion, I tuned down my ambitions and done the following:

• Remove conda-environment.yml as discussed in #6 (closed)
• Change distutils import into setuptools import
• Added documentation explaining the rationale behind the dep handling