Index the sources of cpython and use the indexed data.

- This is a step towards being able to use cinspect for any C sources.

- The indexing is really slow as of now.  This can be easily improved by
  clubbing all the different indexers for function definitions, module
  definitions, and type definitions.

- The indexes are stored in a dumb way, and there are still some assumptions
  specific to the way things are named.  This should be removed!