KJ-4 Convert typed expressions into expressions with casts .
Introduced a new step for elaboration of block-level termsL elabEnd, between elabDispose and elabRes. When all children of elabDispose(KL(...)) have been unwrapped from their elabRes() wrapper, the head term changes from elabDispose to elabRes. this simplifies some custom rules for elabEnd - now they don't have to check the form of their child nodes.