Hey, I updated the MD5 import/export addon by nemyax to support Blender 2.8. I also changed it to allow batch importing/exporting of animations as actions into Blender, as opposed to using markers on the timeline.
Link:
https://github.com/KozGit/Blender-2.8-MD5-import-export-addon
Make sure to read the docs, there are a few changes, like the use of collections for import/export.
Let me know if there are issues/questions/suggestions.
Thanks for the energies providing an updated MD5 script, it's still surprising popular as a format.