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,

The code converting maximal cliques to coalitions of CL is now much more
readable.

As ocaml is not purely functional, the following code snippets have
different semantics:

    List.map (List.fold_left tmpf (bsetMakeRealEmpty ()))
             (List.map S.elements intlist)

vs

    List.map (fun x -> List.fold_left tmpf (bsetMakeRealEmpty ()) x)
             (List.map S.elements intlist)

The former code calls bsetMakeRealEmpty only once, but the latter calls
ot for each element of the list returned by the (map ... intlist).

Because of this, all coalitions were merged into one big set, i.e.
there always was only one coalition: the union of all maximal disjoint
sets. This of course triggered bad behaviour, which is fixed now by this
commit.

The code is unreadable anyway and will be improved a lot by the
following commit.

This closes #13