SPC for FFT question

[ChrisBeeley]

Lots of trusts seem to have SPC charts for the ticky box FFT question (although ours doesn't). We should add it as an option.

For the purposes of the repo we can make fake FFT data because we don't need to publish actual FFT data on here

[milanwiedemann]

@ChrisBeeley let's talk about this in next meeting, want to clarify what you mean

[milanwiedemann]

@ChrisBeeley I think we forgot to talk about this. I'll try to figure this out by myself, if I cant find the data you'll hear me shout for help

[ChrisBeeley]

Closed by #24 , but it's very imperfect. I'll file another issue after meeting with the customers to refine what we need to do with it