Add netcdf archive

[pingelit]

It would be great for use cases of this library, if it would support serializing to netcdf files. The data structures are not fully aligned but with a bit of extra information, I think it would be possible.

One option could be, that the polyscribe wrappers would also accept an optional dimension keyword or tuple for higher dimensional variables. Though depending on where they are applies one might suffice. This would also be easy to add to the webidl definition. While serializing the dimensions coordinates might then be supplied (or left blank).

This idea is not fully thought through yet, but I think it is possible.