* Sanitized the shell command examples of extraneous whitespace.
* Removed keycount.c as sanitising it is pointless and it will be
generated by Cython when the example is followed.
* Regenerated the .texi version.
* 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.
