Get metrics about Python Standard Library

The goal of this project is to answer the questions:

 - what are all functions that are shipped with Python?
 - where are source files for a given Python module?
 - given path in Python repository, find a module or
   function to which it belongs

Directory contents

dataset/paths  - files containing all file paths in
                 Python source code for every version      - script that updates dataset/paths

- stdlib.json  - mapping of stdlib source code paths
                 to module names

-  - script to retrieve module statistics

  [x] open patches per module
    [x] get list of all open issues with patches
    [x] get patch files for each issue
    [x] extract paths from each patch
    [x] detect modules for the issue using paths
    [x] print list of modules and issues

-  - module to query stdlib info

    getmodname(path)  - get module name for the path
    checklib(srcroot) - show stdlib.json coverage


  [ ] build/check stdlib.json automatically
    [ ] check all paths in stdlib.json are actually
        present in CPython source code
    [ ] ingnore unknown files with proper reason
  [ ] compare stdlib.json contents with Sphinx list