Make parentheses visible while under `matchingbracket` rule

**Code**: Brackets now become black when they are highlighted as "matching".
**JSON**: key names are now in "white" (json was a bit saturated with orange - keys and string values).
**Cleanup**: removed some unnecessary rules.
**Default face**: color normalized to #ffffec (was #ffffe9).
I'm not a fan of `!important` rules. Don't the two classes already give this enough specificity to take precedence in all actual situations?