Add configuration files

[eggplants]

I added requirements.txt, .gitignore, and .python-version for pyenv and pyenv-win.

Create env with pip

pyenv install 3.6.8  # pyenv-win
pyenv install 3.6.14 # pyenv
python3 -m venv venv
source ./venv/bin/activate # linux, mac
.\venv\Scripts\activate    # win
python -m pip install -U pip
python -m pip install -r requirements.txt
...
deactivate

Create an conda env with requirements.txt

conda create -y -n ezTrack -c conda-forge python=3.6
conda install --force-reinstall -y -q --name py36 -c conda-forge --file requirements.txt
conda activate py36
...
conda deactivate