Adds keyboard ergodox_extended

[Gephorian]

Description

This adds the Ergodox Extended, a version of the ErgoDox that adds F-keys and expands the thumb cluster. Keyboard hardware repo is here. Firmware is almost entirely based on keyboards/handwired/pterodactyl, since that was very cleanly written and easy to modify.

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout/userspace (addition or update)
• Documentation

Issues Fixed or Closed by This PR

Checklist

• My code follows the code style of this project: C, Python
• I have read the PR Checklist document and have made the appropriate changes.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[Gephorian]

I think that's everything, if I missed anything please let me know and I'll get it sorted asap.

[Gephorian]

Alrighty, got all those changes committed. How are we looking?

[zvecr]

Looks to be unused, though i havent built locally to verify

[Gephorian]

Anything left to do here?

[Gephorian]

I think this is ready for review/merge, all the changes requested have been made and it's looking pretty sharp. If there's anything else I need on it, let me know and I can get it fixed up immediately.

[Gephorian]

Ready for merge?

[Gephorian]

Done. I think that should be the last thing, right?

[Gephorian]

Good morning! This is ready for a review. Let me know if anything else needs to be changed. I'd love to get this merged this week if possible.

[Gephorian]

Anyone free to have a look at this and let me know if anything else needs to be changed?

[lesshonor]

(note: I don't know enough about the custom matrix to comment on it one way or the other, but everything else seems fine.)

[Gephorian]

At the very least, the custom matrix works as intended. I've been typing on it for a bit.

[Gephorian]

This has been approved for a month. Can I get this merged in?