On the way to get the combined prefit converge including uncertainty estimate

Needed ingredients:
 - at least new merging with threshold 0.5 (and consistent pruning file)
 - maximally reduced uncertainty model as implemented in data/limit-config-sm-131113
 - only tested to converge for main htt channels (mt et em ee mm tt) vhtt has not yet been added, cross fingers that it does not disturb the whole thing too much