[handle empty tuples properly when converting to grin from core
John Meacham <john@repetae.net>**20070602100932] hunk ./Grin/FromE.hs 134
+    toty (ELit LitCons { litName = n, litArgs = [], litType = ty }) |  ty == eHash, TypeConstructor <- nameType n, Just 0 <- fromUnboxedNameTuple n = TyUnit
hunk ./Grin/FromE.hs 677
+        f x | Just [] <- literal x = Unit