Bug#692852: dolfin: Avoid hardcoding the swig2.0 version

[Ralf Treinen]

This has now made python-dolphin not installable in sid since the version of
swig in sid has passed to 2.0.8-1 on 2012-10-31. However, python-dolphin still
depends on swig2.0 (>= 2.0.7), swig2.0 (<< 2.0.8~).

Hence raising severity to serious.
-- 
Ralf Treinen
Laboratoire Preuves, Programmes et Systèmes
Université Paris Diderot, Paris, France.
http://www.pps.univ-paris-diderot.fr/~treinen/
=====> New email address: treinen at pps.univ-paris-diderot.fr <=====