I had troubles with distutils 1.0 and the way I use SWIG.
I couldn't find any support for the -shadow option and no way to pass an
extra include dir to swig (like it´s possible for the c compiler)
Therefore I wrote a patch.
It adds an extra_swig_args (list of string) option to Extension.
All the strings are passed to swig without modification, but
if extra_swig_args contains...
