Following Elad Shahar advice (cf. #4368), let's delete whirlpinch.py and
clothify.py.
The rational is that whirlpinch.py does the same thing as the existing
"plug-in-whirl-pinch" which is itself a compat plug-in to
"gegl:whirl-pinch" operation. Also the Python file has an explicit
command saying it is exactly the same algorithm, yet with no preview and
slower. Finally it was not even installed on stable build. It doesn't
look like there is any reason to keep it (it was probably a demo/test
Python plug-in).
As for clothify.py, a quick look at the short code shows it is exactly
the same algorithm as clothify.scm, with the same arguments and
installed on the same `Filters > Artistic` menu (except that the Python
version is not installed on stable builds).
So let's just keep the script-fu version as it has been the used version
until now, and there is no deprecation going on in one side or another.
So let's keep what already works.