#KJ-65 Replace objectClosure() with some cells structure. Implemented part 1:

Create the cell <objectStore> as a collection of <object>, each of them holding an <objectClosure>. Do not refer to objectClosure() in <store>, refer to them in <object> for other purposes than retrieving their id. Outside <object>, e.g. in <k>, replace usages of objectClosure() with objectRef().