80-column compliance
Examples are not properly part of the langid package.
Split langid/langid.py into core classifier and UI.

langid/identifier.py contains the core classifier, only.
langid/ui.py contains the command-line and HTTP interfaces.

langid/__init__.py reexposes all of langid/identifier.py's exports, so
you can now do (for instance) "from langid import LanguageIdentifier".

New top-level langid.py is the command-line driver.

Ancillary changes to langid/identifier.py:

 - use pkgutil.get_data to read model.bz2
 - for user-supplied models, support uncompressed, gzipped, and (in Py3)
   lzma-compressed pickles, with or without base64
 - restore the original from_model()/from_modelpath() API
 - remove some silly dynamism tricks that would've made Cythonification
   harder
Repickle using protocol 2 for ~40% file size reduction.