In calls to pow, sqrt, std::min, std::max, cast to float or double to remove compiler errors on Windows. Fix occlusion of std::min, std::max on Windows.

git-svn-id: svn+ssh://portal-auth.nersc.gov/project/projectdirs/visit/svn/visit/branches/2.7RC/src@21930 18c085ea-50e0-402c-830e-de6fd14e8384