Support Defragment of TDMS File

[jimkring]

The npTDMS library has a defragment function (here) that's very useful. It would be great to have similar support for this in tedium. It's probably use it to create a CLI tool I can run on embedded (NI Linux RT) systems :)

[JamesMc86]

Just for a record, at the core for the data we probably need something like:

fn copy_channel_data<D: TdmsDatatype>(source, dest, channel) {
    generic_read()
    generic_write()
}

fn copy_channel(source, dest, channel) {
    let type = source.get_channel_type();
    match source.get_channel_type(channel) {
        f64 => copy_channel_data::<f64>(source, dest, channel)
    }
}

Then at a higher level you want copy_all_properties and copy_all_channels

You could try and optimize it so the same length channels are all written in the same block but that may be a stage 2

[jimkring]

Thanks @JamesMc86. I've started on this suggestion in PR #40. I'm learning Rust as I go, so the code will definitely need some refactor/cleanup :)