* Initial test to allow math in distances.
Support + and -
Needs spaces around + and -.
* [THEME] Fix printing theme with math in distance.
* [Theme] use calc() syntax.
* [Theme] Add * and / to calc().
* [Theme] Fix the precedense ordering in parsing. Also avoid making copies.
* [Theme] Don't print unneeded ().
* [Theme] Add modulo to calc.