fix toolbox.doctest under Py3k
Fix nltk.misc.wordfinder tests under Python 3.x by skipping them :)
nltk.util doctests are fixed for Python 3.x
fix LazyCorpusReader._unload once again
Fix corpus.doctest (I have no idea why it starts failing again)
corpus.doctest is fixed for Python 3.3
Some stability issues in resolution.doctest are fixed by making AbstractVariableExpression orderable and BindingDict.__str__ stable.
Merge pull request #344 from alexrudnick/master

Two fixes for nltk.downloader