when using unique_ptr for arrays, they are cleaned up by calling
`delete[] bla.release()`.
At least, cppreference says that the release method
"returns a pointer to the managed object and releases the ownership ".
https://en.cppreference.com/w/cpp/memory/unique_ptr

very simple functionality, but I gain two lines per value in the useful
file, which I consider a big deal.

incidentally, it looks like the binary reader is working.