Corected bug in def of dropWhile (also present in Haskell lib!)
Corected bug in def of dropWhile (also present in Haskell lib!)

MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle