Merge branch 'master' of https://github.com/mjakeman/easel

Merge pull request #4 from mjakeman/qol-changes

v0.3 - Auto Updating / Misc Changes

Cleanup + Reorganisation (#3)

* Experiment with rewriting the UI in React

* Reimplement existing UI in React

* Slight Organisation/Renaming/Clean Up

Fix release.yml

Upload xpi instead of zip

Support signing add-ons