... and arrays of values in caps while at the same time refactoring the
Value code a bit.

IntoIterator did not work as expected anyway and would require usage of
AsRef, which then breaks type inference for empty slices for example.

stop should only really fail if everything is broken, but we can always
recover somehow here.

Only Speex, AAC and H264 are missing now, which require a little bit
more work.

This is not too nice now as we have None values to unwrap, but the code
is at least less convoluted.

It has the needed changes now