interface/python.cc: document order of superclasses
interface/python.cc: document order of superclasses

In particular, explain that the order of the superclasses is
the opposite of the order of the corresponding annotations.

Signed-off-by: Sven Verdoolaege <e5350bbed4977f5eb8ae1dc6abd9ae59d21ace75@kotnet.org>

PollyLabs/isl,tobig/isl,UBERTC/isl,nicolasvasilache/isl,Meinersbur/isl,PollyLabs/isl,nicolasvasilache/isl,tobig/isl,PollyLabs/isl,inducer/isl-mirror,PollyLabs/isl,inducer/isl-mirror,inducer/isl-mirror,inducer/isl-mirror,Meinersbur/isl,nicolasvasilache/isl,Meinersbur/isl,UBERTC/isl,UBERTC/isl,tobig/isl,nicolasvasilache/isl,Meinersbur/isl,inducer/isl-mirror,PollyLabs/isl,tobig/isl,UBERTC/isl,nicolasvasilache/isl