Enable pip installation

[densnow]

This is what has been done:

• Add src directory as "project root" with README and pyproject files, as well as algoesup package directory.
• Split algoesup.py into modules test.py, time.py and magics.py to seperate Ipython from regular python and added them to the algoesup directory.
• Add load_ipython_extension() function to magics.py to enable magics to be loaded and registered with %load_ext algoesup.magics
• Add simple one-liner module docstrings to each module.
• Add __init__.py file which imports the main functions from test.py and time.py so user can import with from algoesup import ... instead of from algoesup.time import...

This seems to be working in terms of a local pip installation in 3.10 and 3.11 clean environments on Linux.

This is what has not been done:

• Build the package with poetry
• dev-dependencies in the pyproject.toml (Do we want to use poetry for the development environment like allowed does?)
• Move any examples from the writing guidance to Library section (maybe this is a separate issue?)
• Change the docstrings. Although I did experiment with a google style docstring on the mkdocs branch and it created a nice table of parameters and some examples very easily (again this is probably a separate issue?)

As always, comments, suggestions and pointers to extra steps needed are welcome. Thanks