bugfix: it is illegal to use "class" in this context, "typename" is correct....

bugfix: it is illegal to use "class" in this context, "typename" is correct. Strangely enough, newer gccs have no problem with that, but gcc 4.3 does. Approved by Alex.

git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@11707 2fb0f335-1f38-0410-981e-8018bf24f1b0