Improve installation procedure

[wardsimon]

Pip installation

In this pull request we deal with installation. It is now possible to:

For users

pip install --extra-index-url https://easyscience.github.io/pypi/ .
easyDiffraction

For developers

pip install --extra-index-url https://easyscience.github.io/pypi/ -e '.[ci]'

Notes

In the installation an additional --extra-index-url https://easyscience.github.io/pypi/ is added due to CFML not being released

Snapcraft images

A snap image is also made by default and can be used on Linux based systems. When this work hits the master branch, the application can be found on the snap store. In the meantime the build artifact can be installed with:

snap install --devmode easydiffraction*.snap

[rozyczko]

Clean Ubuntu 22.04

pip install . gives me

ERROR: No matching distribution found for CFML<0.0.2,>=0.01

snap install --dev-mode easydiffraction*.snap gives me

error: unknown flag `dev-mode`

pip install -e '.[dev]' gives me

ERROR: File "setup.py" or "setup.cfg" not found.
(A "pyproject.toml" file was found, but editable mode currently requires a setuptools-based build.)

[wardsimon]

Yeah, this is still the problem with no CFML release, you meed the --extra-index-url https://easyscience.github.io/pypi/. I've updated the main text.

It should be --devmode

It should be '.[ci]'

[rozyczko]

This works properly on Ubuntu 22.04 for the first two modes. Installing from snap will of course be tested only after the merge.

[wardsimon]

This should now be OK to merge