handle posix class negation
handle posix class negation

Ignore-this: 59e00c59cf894eb8be9d2df353ca810a

darcs-hash:20100119190708-c41ad-49a26ab3c29cbf60c5d8b5f68c5de8c15860bca0

vbmithr/ocaml-text,vbmithr/ocaml-text