Using `dashicons-edit` for icons (because it's a pen)
Refactor all editor-related functionality into separate class
Properly localize scripts
Add button and pop-up (though they don't do anything yet)
Create "Insert Gistpen" button and fugly pop-up to insert Gistpen shortcode with ids
Begin migrating to SASS instead of CSS
Clean up border
Add Create Gistpen radio button
Create shitty looking form that can insert or create a new Gistpen from the editor