Eliminate Deprecated Constants

[oleibman]

In Theme, change COLOR_SCHEME_2013_PLUS_NAME to private (use COLOR_SCHEME_2013_2022_NAME instead), and delete COLOR_SCHEME_2013_PLUS (use COLOR_SCHEME_2013_2022).

This is:

• a bugfix
• a new feature
• refactoring
• additional unit tests
• cleanup for new major release

Checklist:

• Changes are covered by unit tests
  • Changes are covered by existing unit tests
  • New unit tests have been added
• Code style is respected
• Commit message explains why the change is made (see https://github.com/erlang/otp/wiki/Writing-good-commit-messages)
• CHANGELOG.md contains a short summary of the change and a link to the pull request if applicable
• Documentation is updated as necessary

[oleibman]

Scrutinizer failed setting up its test. No idea why. Don't really care.