- Updates scss variables file to use better-named variables for black/white/etc
- Arranges the "mastodon classic" colors into variables
- Remove all references to `$color-*` naming, replacing with new
This does not in itself introduce "theme" support, but:
- It would probably be easier to start working on theme support after this
change and others
- Even without the goal of themes, these changes make it more clear how the
colors are being used.
There is almost definitely some edge case in here where I've guessed the
intent/context of some color usage incorrectly, but it still seems like a net
improvement.