Generate case-tree constructor for all tactics

At the moment, the case-tree constructor in the configuration object is only properly generated for Intro and CoSplit. It should be generated for Split and any other tactic as well. This is a potential bug when the tactics are applied in a different order. Moreover, we can then use this constructor to generate the case-tree in Done. The configuration object is perhaps not the right place to store the constructor. Maybe the signature of a tactic is better suited for this parameter.