ddc-core-flow: implement sliceVector for packs
ddc-core-flow: fix packme test where the flags are a process parameter
ddc-core-flow: follow Nat/Int munging in tests
ddc-core-flow: intersperse: reorder bindings when extracting
ddc-core-flow: slurp simple cases, by 'inverting' the case into a let and case for each datacon rgument