Issue with IrToy and IrScrutinizer on Linux

[Barf]

The Linux kernel 5.9 (released a few months ago) radically changed the way IrToy (and its copy IrDroid) is supported under Linux.

Short version: For kernel version >= 5.9 the IrToy hardware does not work in IrScrutinizer. Instead, use the /dev/lirc hardware interface. However, frequency measurement does not work there.

Long version: see this.