Move ConnPlotter code from NEST to a separate repository

[pnbabu]

Fixes #1971

This PR moves all the files related to ConnPlotter from nest-simulator repo.

[jougs]

Looks mostly good. I'm wondering a bit if the toplevel Python files (other than setup.py, that is) should go into their own src or nest-connplotter directory instead of being toplevel.

I'd also like to hear @heplesser's feedback as original author before merging

[jougs]

And I think that examples/__init__.py can go. It does not have anything useful.

[heplesser]

This move is fine with me. "examples" is currently set up as a package, thus examples/__init__.py. But having it as a package does not really make sense, so the __init__.py should be removed. This has consequences:

• connplotter_tutorial.py relies on examples being a package, but that should be easily fixed.
• Also setup.py treats examples as a package and needs to be adjusted to ensure that the examples will be installed.

Finally, the tutorial is in a very outdated literal programming format, it would be great to convert it to a notebook or our standard style for examples.

[pnbabu]

Removed examples/__init__.py and updated the tutorial and setup.py accordingly.

I am trying to run the tutorial locally on my machine and it is taking a long time to run. I will investigate what is taking time. @heplesser When you say standard style, are you referring to pynest/examples in the NEST repo?

[Helveg]

Oh I think I did some duplicate things in #2. Some things that should be taken from there:

• import matplotlib.font_manager, not all version of matplotlib import this when mpl is imported and an AttributeError can occur (happened to me on v3.4.3)
• In setup.py:
  • Replace from distutils.core with from setuptools; distutils is problematic and deprecated (will be removed in Python 3.12). distutils packages cannot be uninstalled by pip for example.
  • Remove the package_dir argument and place source code files into a ConnPlotter or nest_connplotter directory, then just give packages=["nest_connplotter"] for simplified and conventional packaging.
• Add a .gitignore

[jougs]

Work and discussion continues in #2.