Add a cython example of using the LWT interface

[benjeffery]

We have basic C examples - would be good to have cython also.

[benjeffery]

See #1004 (comment)

[benjeffery]

Hopefully with the recent numba developments this isn't so needed, please get in touch if you need cython tips.

[benjeffery]

Actually turns out that @terhorst had done the haard work over at #1124!

[terhorst]

Whoah blast from the past :-) Sorry for losing track of this.

I rarely use Cython these days, Numba turns out to be much better/lower friction for my work. Numba supports calling C code via CFFI. I wonder if you all have ever experimented with CFFI and tskti?

[benjeffery]

I certainly haven't played with that - thanks for the pointer.