Convert to proper python package

[Peter9192]

We could restructure the repo like so:

moisture_tracking_intercomparison/
    pyproject.toml  # package metadata such as name ("itrack? wetrack?"), version, dependencies
    src/
        itrack/
            __init__.py  # empty file
            postprocessing.py   # contains data reading code: from itrack import postprocessing
            analysis.py    # contains code for making standard plots

    # not part of python package, but still useful
    notebooks/
        boxplots.ipynb
        ...
    scripts/
        standardize_data.py  # script to convert from "raw" to "polished" data.
    README.md  # documentation
    LICENSE
    CITATION.cff  

Then you can do pip install --editable . to install the package in "editable" mode,

or, given that we migrate and rename the repo, anyone could do
pip install git+https://github.com/moisture_tracking_community/itrack

and, if we publish it on PyPI, anyone can do pip install itrack