Remove all SDL related code, fft_eval is now useless but still compiles

Signed-off-by: Gui Iribarren <gui@altermundi.net>
Print data in JSON format

Signed-off-by: Gui Iribarren <gui@altermundi.net>
Rename function draw_picture to print_values and cleanup vars

Signed-off-by: Gui Iribarren <gui@altermundi.net>
Adapt README and add me as author

Signed-off-by: Gui Iribarren <gui@altermundi.net>
drop now unused font/ directory