Add support for building with pip / pyproject.toml

[jatkinson1000]

Currently poetry? but with conda files kicking around.

Suggest we start by:

• Pull out conda, poetry, and any other mix of existing installation code
• a simple pyproject.toml installation that can be build by cloning and pip install -e .

Then add in other desired build systems once code is working.

[jatkinson1000]

Discussed with @raehik
Potential workflow:

• Branch off of first commit to repo (new_main)
• Change build system
• Open pull request
• Eventually archive main and then write main-new onto main.

[raehik]

Working on building with pyproject.toml / pip at #13 .

[jatkinson1000]

As suggested by @christopheredsall once there is something simple that can be pip installed we might want to tag it as 'alpha' or 'pre-release' so that there is something that works and closely reflects the original; paper code before we start merging other development branches.

[jatkinson1000]

main has now been moved to src_and_poetry, with main_new being moved to main.
To bring local copies into line please run:

git branch -m main src_and_poetry
git branch -m main-new main
git fetch origin
git branch -u origin/src_and_poetry src_and_poetry
git branch -u origin/main main
git remote set-head origin -a

from within your local clone.

PR #13 for the overall packaging issue is now targeting main.