Check multiple queries at once

[NicEastvillage]

A cool property of our approach is that every assignment of a configuration directly describes a pair in the satisfaction relation, thus a configuration like ⟨{x: 2, y: 5}, x < 10⟩ will always get the same assignment. This means we can reuse configurations and assignments across queries.

We should therefore allow the user to check multiple queries at once (either multiple formulas in the same file and/or multiple files) and we should reuse the dependency graph and assignments across queries. This would allow us to terminate faster if any of the queries have dependencies in common.