Handle single prec in rfft and irfft.
Handle single prec in rfft and irfft.

git-svn-id: 003f22d385e25de9cff933a5ea4efd77cb5e7b28@5358 d6536bca-fef9-0310-8506-e4c0a848fbcf

lesserwhirls/scipy-cwt,jasonmccampbell/scipy-refactor,lesserwhirls/scipy-cwt,scipy/scipy-svn,scipy/scipy-svn,scipy/scipy-svn,jasonmccampbell/scipy-refactor,scipy/scipy-svn,jasonmccampbell/scipy-refactor,jasonmccampbell/scipy-refactor,lesserwhirls/scipy-cwt,lesserwhirls/scipy-cwt