ddc-core-flow: make thread transform handle local loops
ddc-core-flow: make Wind be sensible when there are no accumulators
ddc-core-flow: add another Thread test
ddc-core-flow: fixing bugs in Thread and Wind transform
ddc-core-flow: use correct tuple result size in Wind
ddc-core-simpl: give proper config to Forward
ddc-core-flow: wibbles on Forward transform