Strange formatting when requesting string format of Waveforms

There's an odd behaviour when you request Waveform data in `string` format. It seems `numpy` adds "\n" characters into the returned array - it seems to be trying to format it for nice line wrapping.

We don't want this behaviour. We should investigate [this function](https://numpy.org/doc/stable/reference/generated/numpy.set_printoptions.html#numpy.set_printoptions) to find the correct way to suppress this feature - probably by changing the `linewidth` parameter