Replace recordtype with namedlist

[jan-janssen]

Mandatory Checklist

Please ensure that the following criteria are met:

• [x] Title of pull request describes the changes/features
• [ ] Request at least 2 reviewers
• [x] If new files are being added, the files are no larger than 100kB. Post the file sizes.
• [x] Code coverage did not decrease. If this is a bug fix, a test should cover that bug fix. If a new feature is added, a test should be made to cover that feature.
• [x] New features have appropriate documentation strings (readable by sphinx)
• [x] Contributor has read and agreed with CONTRIBUTING.md and has added themselves to CONTRIBUTORS.md

As a general rule of thumb, try to follow PEP8 guidelines.

Description

recordtype is no longer updated the successor is named namedlist: https://github.com/timgates42/namedlist So I updated the reference to recordtype and replaced it with namedlist.

[cekees]

Not sure what is going on with the tests. I need to take a closer look, but I may not get to it today. @jhcollins do you have a conda-based installation you could try to test locally?