NeuralynxIO: Factor out header handling.

[PeterNSteinmetz]

This factors parsing the NlxHeader into parts and provides an option to construct without testing for time and date.

[PeterNSteinmetz]

This is failing because the test data are not in ephy_testing_data yet. For that I am waiting on clarification of how to check the files in. See the google groups thread "New workflow with datalad?"

[zm711]

Regarding your google group message about incorporating some of your local code. Could you describe a bit more what it is doing? I think making things more robust/flexible would be great, but it also needs to fit within the Neo framework. So you can either open an issue to discuss what you're proposing if you have a hunch that your code might be bigger changes to neuralynx. Or you could open a draft PR and see what happens in the test suite with the rest of the code if you incorporate some of your code.

[PeterNSteinmetz]

I added pull request #116 for ephy_testing_data for the dataset which will allow this to pass checks. That pull request on the dataset should be ready to go.

[zm711]

@PeterNSteinmetz , @samuelgarcia is going to look over everything very soon for your recent PRs so you'll have feedback on everything asap.

[samuelgarcia]

Hi @PeterNSteinmetz.
I remove the new tests for now and I will merge this into main.
So I can start also a PR on top of it.
I let you open a new PR when files are ready.