Remove redundant function spaces and simplify file creation, switching to XDMF files
Remove redundant function spaces and simplify file creation, switching to XDMF files

Johnson-A/UNM_Research,Johnson-A/mantle_simulation,Johnson-A/mantle_simulation,Johnson-A/UNM_Research,mroyluna/summer17mantlesim,Johnson-A/UNM_Research,mroyluna/summer17mantlesim,mroyluna/summer17mantlesim