Changed frame() to accept either a frame id or frame name, as suggested by Nathan Schneider
Added pretty printing for AttrDict objects. Also changed the frame() function to use nltk.compat.string_types
Merge pull request #469 from wooters/master

Changed frame() to accept either a frame id or frame name
fixed nltk downloader tkinter.messagebox import
Merge pull request #471 from jskda/pull_request.nltk_download_gui

fixed nltk downloader tkinter.messagebox import