Took a lot longer than I would have liked to figure this out! Also: don't use data_files or package_data

Evidently not returning a value from a function that should causes some weird behaviors with (ierr != 0) not working properly

Needs some testing yet, and to be made a first-class citizen

Don't compile in clang

Small computational speed bonus

(but maybe the compiler elides all the copies anyhow)

Some more testing is needed, but looks promising so far