separate tests for basic ListADT fns (->Str, ctors, predicates) from the rest; add some tests for validity of return values from extra ListADT fns
LambdaGrammar: quote symbols 'λ' and 'δ' to make parrot happy, rename method λ to parseLambda
move primitive projections to Base.pm6, name them piXoY (lambda-names πY->X), make them scalar constants