new checkZrank() and checkNlevels() utilities for *some* modularization of
 lFormula() and
glFormula()    --- which I think should be one function --

tests now work, all up to the unit tests ('tests-all.R') which "almost surely"
is unrelated to this change.
glFormula() returns list() the same as lFormula()
testLevel cosmetic; update the *.Rout.save ones