It looks like [CaDiCaL](https://github.com/arminbiere/cadical) is faster than Glucose, so we want to at least support CaDiCaL. - [ ] Minimal support: support using CaDiCaL as a backend when only normal clauses exist - [ ] Support special propagator with CaDiCaL (to do this, we should make CaDiCaL a CDCL(T) solver)
