Some options and functions are still missing, e.g. MILP support

Introduce a new generic data type lazylist, e.g. used for lazy rule
enumerations.

Propagation of satisfiability and unsatisfiability does not cover
disjunctions and I don't get how propagation works, so I won't touch it
yet. So this reverts the only partially implemented Disjunctive
ruleEnumerations,