Skewy - anti eavesdropping

Dec 20, 2022

New features:
** User can now select their own sound or chose between the two Skewy mixes (in options menu).
** Ultrasonic jamming tone now includes two different frequencies.

Bug fixes:
** Crashes when turning the recorder off.
** Switch "Jam ultrasonic signals" sometimes displayed as off - even though it was turned on.
** Crash when selecting 0 as signal length (happened by just hitting "apply" without changing the slider).

Misc
** New images for the signal detection tutorial