Hooks for pylint, astroid and accompanying fixes.

Add: Hooks for pylint and its dependency, astroid.
     Optional subdir parameter to hookutils.collect_data_files,
       .collect_submodules to support pattern of run-time imports in a directory
       lacking __init__.py.
     Tests for pylint.
Fix: Pylint prints out lots of output, which isn't ready by runtests.py. Be sure
       to read all stdout when the process finishes.
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