Explicitly mention setuptools 0.6 in install.rst

Setuptools merged with Distribute in 0.7. I think setup.py needs to be migrated to 0.7?
fixed chunk/regexp.py chunk parser usage examples
use _im_class instead of im_class to avoid conflict with nose.suite.ContextSuiteFactory.ancestory seeing the compat module as a class
Merge pull request #429 from jskda/master

nltk fixes
fixed xml encoding detection bug, can be reproduced by the following code: "from nltk import book"
Merge pull request #430 from jskda/master

PY3 fixed xml decoding detection bug
PY3: fix nltk.classify.tadm
rename compat._im_class to compat.get_im_class because it is not private
improve word_tokenize speed

Runs roughly twice as fast on my test set of 40000 sentences. According
to kernprof (http://pythonhosted.org/line_profiler/), the culprits of the
previously bad performance were

    r"([^' ])('ll|'re|'ve|n't|) "

and

    r"([^' ])('LL|'RE|'VE|N'T|) "

which were matching all words due to the | at the end.

Also removed some useless whitespace handling that was being undone by the
str.split just before return.

The contractions handling is now the slowest part @~20% of the time.
Merge pull request #434 from larsmans/faster-word_tokenize

improve word_tokenize speed
removed stale test framework
Merge pull request #432 from dougalg/master

Changes to wordnet lowest_common_hypernyms
Merge pull request #425 from pfeyz/patch-1

Explicitly mention setuptools 0.6 in install.rst
open gzip files in text mode in the tadm classifier trainer
Merge pull request #436 from jskda/pull_requests

open gzip files in text mode in the tadm classifier trainer
fixed failing doctests, caused by floating point precision issue
Merge branch 'master' of https://github.com/nltk/nltk
tests now live inside module
finalise changelog for next release
pull fixes to setuptools, cf https://github.com/nltk/nltk/pull/437