Summary
- merged
- simplified -- avoid odd mutable state, which potentially causes problems with module initialization;
- back to static Mixfix.default_constraint without any special tricks (reverting e6443edaebff);
- Type_Infer.object_logic controls improvement of type inference result;
- tuned;
- simplified constraints;
- back to dummy constraints (amending dd2914250ca7): important for Syntax_Phases.get_free/is_declared;
- tuned imports;
- tuned message;
- tuned;