Note this commit leaves out the biggest occurrence of the editor
which is the post/topic composer.
To avoid major breakage, this replaces it everywhere else it was
used:
* User preferences (About Me)
* Admin Customizations > Text Content
* Category Templates
* Editing Queued Posts
A future commit will replace the main composer with this editor
and will remove the unused pagedown code.
- Moves the import of plugins for both mobile and desktop from common after discourse loading, allowing plugins to overwrite
- Make desktop-option behave like the mobile-option: SCSS/CSS marked with that option will only be loaded for desktop from now on and ignored in mobile
- Add variables-keyword, allowing plugins to ship and overwrite variables before they get imported by discourse (great for theming)
