* Added new advanced section with an example of using the Python
  bindings with CPython code compiled back to C code using Cython.
* Though it may seem a bit counter-intuitive to use the bindings just
  to go back to C via a different route, this is not actually stupid.
* Added examples/howto/advanced/cython/ directory.
* Added keycount.pyx, setup.py and the keycount.c file which the first
  two generated with Cython.  Not including the .so and .o files from
  the build.
* Exported the .texi version of the howto for the main docs.