Closes #1304

https://github.com/bithatch/snake

This doesn't work well when the task is backgrounded and is not really
useful.

This option creates problem with the event files.

Reason is that the created event files are fifo pipes which - if not
opened on this side - will block on the other side (the daemon) and hang
forever. So we need to keep these pipes open to not make the daemon
misbehave.

This should make it much easier to just create all fake devices
that are available.

Previously we would always read the serial number and sleep 0.1 seconds
even if querying the serial number has succeeded. Move the sleep to only
sleep when really needed.

This decreases the init time of the daemon for ~80 devices from ~10
seconds to ~2 seconds.

sort the list alphabetically while we're at it

Without this, a FileNotFoundError is thrown:
/tmp/daemon_test/0003:1532:0207.0001/kbd_layout

Fixes #1240

Fixes #949

Additionally the dual/triple functions have been switched to have them
in logical order.

See #1164 for details.

This has been deprecated for quite some time, but provide a shim so
older applications will continue to work as before.
Frontends have only been using one image, so only one device image needs
to be defined.