Download fourier data

[MuLx10]

Added Download button for draw zone. It would help the user to recreate the diagram from the Fourier series data.
Data is saved in the below described format in json.

{"amplitude":[],"phase":[],"frequency":[]}

fourier-data.json

[Jezzamonn]

Hi! First of all, nice job in digging into the code and getting an understanding of how it works. I like the idea of letting people be able to access this data!

Some high-level questions to be resolved though is:

• How do we make sure this doesn't interfere with reading the page? I'd rather not have a button in a prominent place as I think that might be a bit distracting when you're reading the article. Maybe there's a better way to trigger this?
• What's the best file format for the data (is there a reason you picked that format?)
• How do we set this up for the other languages (this page is not just in English!)